100% your dad already knows. Stay in your own lane and worry about you and your life. Your parents have other things going on behind closed doors that you don’t know about and may not understand
58 Likes
Minding your business will always bring you peace. If they’re both good parents to you, it doesn’t matter what they do to each other. Let them divorce, let her cheat, let them argue. Know it in your heart that your parents are their own people and you don’t need to be involved just because you’re their child.
2 Likes
I would gather my
Siblings and your parents. We’d have “a comin’ to Jesus talk”. You girls need to explain that what they have going on isn’t healthy and it is now affecting your relationships with your parents. That for everyone, you all feel divorce is best. This is not a healthy “set up” for anyone, even your kids.
20 Likes
Its between your dad and her. They do not need or want your interference. Your dad obviously knows. Probably just doesn’t care. He may have his own thing going on. You dont know their relationship no matter how much you think you do. Stay out of it. Love both parents.
8 Likes
I know that you are hurt I know that this does affect you but this is really between your mother and your dad and regardless she will always be your mom let those two people handle this situation the more you stay out of it the less you know the better you are going to be I wish you a lot of luck and a very happy life
10 Likes
Perhaps they both know what’s going on and have decided to stay together for convenience, or for practical reasons such as insurance. Every relationship looks different. It’s up to them to decide what works best for them.
It can be traumatizing when your parents split up, but you are grown and I agree with others that you should stay out of it. Spend less time with your mom if you no longer respect her. Be there for your dad if he gets heartbroken and wants the support. But other than that, it’s their lives. Focus on your own instead, before you ruin it by worrying about theirs.
27 Likes
Your mothers a grown woman and sometimes nothing lasts forever, mind your business lol save yourself from the drama you’re stirring up 
9 Likes
Your dad is probably aware of her behavior and it sounds like their marriage is already over in a way with them sleeping in separate rooms and everything but they have their own reasons to not go through with a divorce…you can be mad at her and not agree with what she’s doing but ultimately its between them
8 Likes
Sounds like they may be dealing with their marital problems in their own way. And that’s absolutely their right. There are most likely details that you are unaware of because they don’t concern you. Give your parents the love and respect that they deserve as individuals but do not get involved in their marriage.
7 Likes
Your parents are grown, get out of their business. There’s nothing you can do
8 Likes
Pretty crappy of you to behave this way towards her. She shouldn’t cheat but you don’t know what your dad did to make her care so little. 2 sides. She’s your mother.
7 Likes
Tell your dad and then leave it alone and let them sort it out. If nothing comes about it then you did what you morally could. Imagine if it was hypothetically your spouse cheating on you and your child knew and said nothing. I’d want to know.
7 Likes
Mind your business .
- and to everyone saying it is the kids business …. Is it really though ?
They maybe holding it together for all the kids to be grown if you’ve had both your parents together for this long feel blessed they obviously care enough to keep it together
But parents deserve to be happy too .
Could be a lot more to this story .
6 Likes
Mind ya business. Not your relationship. Not your business. Lol she’s entitled to friends. You don’t just accuse your mom of something without knowing all the details. Just because she didn’t want you to know her password doesn’t mean she’s hiding anything.
6 Likes
Have a come to jesus with both of them if you feel the need. Then you have to back off and let your parents run or ruin their marriage how they see fit. Stop judging your mother. Who knows what’s going on behind closed doors. They’re your parents but you don’t know every single in and out of their marriage. Your dad could be chained up in lingerie at night consenting to all this, getting pegged and having his balls smacked by some stranger with a feathery pink whip and loving every minute. Might be some kind of stag/vixen thing or something more. Do you really need to go that deep to feel whatever it is you need to feel?? Respect them both and mind your own house.
5 Likes
It’s called it’s none of your business her problems aren’t yours. She’s a grown woman and she’s still family. You don’t know everything . If you want answers ask her to sit down with you .
4 Likes
Everyone saying mind your business as if they are living your life. Yeah its good advice but you have every reason to feel the way you feel. To see your family breaking apart and your mom not being honest or faithful to you and your dad. I bet you feel like shes living a double life and you arent part of it. She hasnt put her time and love towards the family she built, and is giving it to other men.
I understand how you feel cause when my mom got on drugs, and would cheat on my dad.
Best advice is tell your mom how you feel. She may validate how you feel or call you crazy but at least you got what you had to say to her off your chest.
4 Likes
I get where the frustration can come from. Possibly mom taught the woman that you don’t cheat and is now being a hypocrite. However, I would stay out of their marriage as much as possible. For all, you know dad already knows and is okay with it. Open marriage is a thing, and they just may not want your kids to know. I’m sure dad is not naive to her not being home or interested in him
3 Likes
All these comments saying “mind your own business” are really pissing me off.
Some of us grew up with 2 parents married happily, some grew up with no parents, some with one parent, some with one and an in and out parent. We do not know her story!!
For all we know they were happily married all of this girls life. And with the issues her parents are going through now, it’s a lot on a person. If she were a child we wouldn’t be telling her this, so why are we telling her to stay out of it now ? No matter how old we are, they are our parents and we are allowed to have an opinion and feelings on what’s happening. Our parents affect us in so many ways. If her parents were the ones together all of her life and now moms cheating , lying etc … it’s not something to just ignore. Her feelings are valid!! She was asking for advice , not to just “stay out of it” because that’s horrible advice for this situation because we really don’t know everything about it right now.
Soooo my advice would honestly be, sit down with your parents and tell them how you’re feeling. Because if your moms cheating she’s clearly not happy. But also, depending how long they’re been together and what not, maybe your dad knows and they’ve agreed to an open marriage and just didn’t know how to tell you. There’s so many different scenarios for this. But my best advice would be to just talk to them. Because that’s really all you can do. Ignoring it and moving on will probably just end up making you feel worse in my opinion.
I hope that makes sense and isn’t jumbled together. My toddler is crawling all over me. Lol
5 Likes
Let your parents handle their marriage, you don’t have to agree with the situation, sounds like your dad truly knows what’s going on, he has either chose to stay no matter what, or he will walk away when he is ready.
3 Likes
Mind your business and love your parents as individuals. Be honest with both of them, your dad isn’t a saint, just the same as your mom. You don’t have all the information, so mind your business and get some therapy. You’ll feel better once you do, I’ve been there.
3 Likes
Tbh maybe he did something first, perhaps that is why he “still takes care of her” 
maybe it’s not all as it appears. People go through things, i wouldn’t judge so harshly, & instead just stop trying so hard to understand because people will need to go through the motions, it doesnt always feel fair, it’s wierd i know. Im sorry for that! But maybe she’s only “acting out” because of something she went through. & if not, I would just let her do her thing, you’re all adults right? She has her personal stuff & you guys have yours. Let her live her life:woman_shrugging:t4:
2 Likes
I don’t think its any of your business to be frank
3 Likes
I suggest you need to cut off anyone who is toxic to you, family or not. I’d be disgusted too, she’s acting like a child and only staying so she can use your father to pay her way through life and she’ll do whatever she wants. Your father needs to grow a pair, man up and put her out of his home. Why hasn’t he divorced her yet? Why are they still arguing? He should cut her off too.
2 Likes
For all you know they could have an open marriage or some sort of agreement because of the circumstances. If that’s the case then all you’re doing is making your father feel uncomfortable/embarrassed and you’re making the entire situation worst… he’s not gonna come out and tell y’all he’s cool with it (he’s probably not) but it’s really nobody’s business anyway (including you or your sisters)
Also, how old are y’all? Y’all blowing up her phone, calling people looking for her and straight up looking for a reason to get pissy! Like WHY!? She’s a grown woman, she raised her kids, and her marriage is between her and her husband.
If I was you I’d find a therapist because the way y’all acting ain’t normal AT ALL
1 Like
None of your business. I’d want my mom to be happy and the best version of herself first and foremost.
3 Likes
You don’t know the full story about any of it you only know what you see on your side. For all you know you’re dad gave her permission to have other relationships. I’d just stay out of it honestly 
1 Like
It’s not your place to do or say anything. I wouldn’t want people meddling with my relationship. Just because they are your parents doesn’t mean they owe you explanations. Let them figure out their own shit.
Better hope your Mama doesn’t blast you on social media when you’re older
8 Likes
As hurtful as it may be, stay out of it. If your dad is not reacting, then🤷♀️ My convo would be with my dad and ask him what he wants to do but end of the day, that’s their business. I would have a convo with mom too but only to let her know certain things I would appreciate not be exposed to my kids, other then that, I would have to mind my own
That is a hard one, what is in your best interest and does it concern you? And if it does then what can u do about it? Honestly is the best policy, and the more serious question What do expect to accomplish if you told them
and what would the consequences for them and you be? You should be able to answer those questions one you do a little soul searching, good luck:pray:
They are ur parents. If u so strongly disagree with ur moms behavior let her know, and then leave it there. Your dad is obviously aware, he just doesn’t for what ever reason want to acknowledge it, respect that. My advice is that if u want to retain a relationship with ur mom, stay out of their marital business.
Im sure it hurts u to think abt your dad hurting, but again its their business.
Stay out of it and mind your own. If they spoke about it before then he already knows. And is quite aware of what’s happening.
1 Like
You are way too much in the middle of your moms business. It seems like you and your sister follow her around and treat her like a teenager. Worry about yourself and let your parents handle their situation.
1 Like
Mind your business. You already told dad. You’ve done your part. Don’t judge someone for how they handle their own inner issues that we all have. Just be a daughter, and maybe trying to talk to her to understand her. You never know what the other side of the story may be.
Just say it to her. “Mum who’s the guy in your phone?” You are all adults of she doesn’t want to explain it to to you let her know she needs to with your dad.
I would leave it to them.
But there is nothing wrong with distancing yourself from someone you think its negatively affecting you. Protect your peace.
It’s easier to stay out than it is to get out. Let them handle it.
2 Likes
Not any of your business. Your parent’s relationship is their private business. I can never understand why some kids think their parent answers to them.
It’s their marriage not yours, I’d honestly want no part of what they have going on behind closed doors. It’s literally between that man and that woman to live their lives how they see fit, you shouldn’t have any say regarding their marriage. It’s none of your business who’s cheating or why. You be an adult in your life and let them continue adulting theirs
1 Like
This is a hard situation to be in. It’s really between your parents though. Granted, it does affect you and yours. I think your mom must be over this marriage with your dad. I’m sure she has her reasons, that’s really none of your business. Just be there for your dad and understand that they’re grown. They are allowed to do what they want, even if what they want is shitty in your opinion. Frankly, I’d point blank ask my mother. It might not be any if my business but if it’s happening with my parents, Imma stick my nose in it too. I’m sure this doesn’t help at all. In the end it might not be your business but you gonna make it yours. Goodluck. I really hope everything works out
Fist of all if they live in the same home but are no longer intimate how is she wrong? People remain together long after the actual relationship has expired. If at any time your dad is not alright with the way things are going in his marriage he has to be the one to decide enough is enough. I wouldnt have let my. Grown children make me do anything. Thats between them. Now any behaviors that directly impact the relationship between you and your mother you have every right to be in ur feelings about. Outside that area thats between her and her husband.
If everyone knows she cheating and neither mom or dad goes and file for divorce then what’s it to you? You can’t make a person act right period. No matter the relationship to you.
Weeeh it’s non of your business with your sis, you can be concerned… But at the end of the day your mom is a grown woman… You and sis should stay out of it
Don’t meddle in their marriage 
Since there is a long history that you may not know all the details you need to separate yourself from the relationship between your mother and your father. There could be more to this story that they have not shared with you. Behind closed doors a lot goes on that people dont know nor do they need to know, especially the kids. I do agree that mom and dad need to keep the kids (even the grown ones) out of their marriage issues. Try to have a relationship with your mother in a way that does not involve what is happening with your dad and the same with him. They may want to divorce but dont for whatever reason so be respectful of that. Maybe your mom has moved on and is defensive because the kids are being brought into their marital problems and she feels ganged up on. Take some time and think about what your mom is going through. You said yourself you know she is unhappy. As for the money… that too is their decision to make. If Dad makes more then he should pay more. They will need to work that out but again it should not involve the kids/grown or not. Hopefully they will find a way to work it out but in the end I cant imagine living in a relationship you are clearly miserable with but for some unknown reason staying. It has to be hard for both of them, try not to add your own issues (with how they are living) on top of it. Sometime our deeds no matter how misguided they are, are done with the best of intentions. Best of luck to all of you.
1 Like
Let me just say I’m SHOCKED by the amount of people saying “its not your business leave it” .
Her mother is clearly over the marriage and using their father as a source of income.
At the very least HE should be made aware. Imagine your significant other making you out to look like a fool while even your own children were aware of it. It’s different when the shoe is on the other foot.
Regardless of who is cheating its NEVER ok.
I think you should mind your own business. There problems have nothing to do with you. They can work it out themselves without you and your sister running and telling your father. Which I’m sure he probably already knows at this point so you’re probably only making him feel worse.
Sounds like it has been over for some time.Both of them need to go there separate ways. Life is too short to keep waiting on a wet match to re-light.
2 Likes
You should stay out of it, you can base your opinion to your mom but that’s about it, she’s an adult and she can make her own decisions and so can your dad, if your dad knows your mom is cheating on him and he doesn’t divorce her then that’s his own problem and shouldn’t be yours or your sisters. If it makes you that mad then distance yourself from your mom.
If there’s a child/sibling living at home with them, then it’s definitely your business. If they’re constantly arguing while your sister is there, it’s your business. It would be their business if it didn’t involve a sibling who can be influenced by their actions. Your mom sounds selfish and toxic, and you don’t have to have her in your life. She probably didn’t go through with divorce cause she’ll eventually have to pay her own bills. Your mom is taking advantage of your dad, and that’s not okay. Your younger sister will be affected by this.
Is this for real?! These kids act like they are the parents… why are they keeping tabs on their mom… she’s an adult.
1 Like
It’s her choice to make these decisions just like it’s your choice on how you respond to her. If you are that hurt or angry choose to distance yourself. She made the choices, let her deal with the consequences. You may tell her your truth and feelings but don’t expect a damn thing in return. Your mother has already proven herself to be a selfish person, take that and move on from it. We learn to be better from watching those around us fall from their mistakes.
1 Like
Been there before. I won’t go into the details but what my dad told me is if he knows, regardless if he does anything, could we call it cheating if he knows. Just be there for your family and don’t have hard feelings, it’ll get better.
Honestly its your dads place to handle the situation. However make it clear that you dont approve of how shes acting and leave it at that. Stay away if u feel u need to your dad already knows cause youve all been telling him. How the situation is handled isnt ur burden and not really your business either. If it changes how you view your mother its ok, thats her own doing and she will need to deal with whatever consequence occur cause of it. Just be an adult
Honest ***
I feel like you must be young ish-(naive,immaturity is what comes to mind) to feel this way over a situation that doesn’t have much to.do with you …it’s your mom’s life not your life you are her daughter yes but not her husband or anything. Let her make her own choices. You don’t know the history of your parents relationship and why she may be doing what she is doing. Or maybe you do…but two sides to all stories…or more.lol
Let her be. Support them both.
1 Like
Unless your mom or dad ask for your opinion don’t give one…your mom and dad obviously have problems but they need to sort it out…
You could say mom I love you but I believe you are stepping out of your marriage and that I don’t like…just because you don’t like something or mad at family member doesn’t mean love stops .
Even if a daughter you don’t know what goes on behind closed doors in a marriage…that is between the two married people…
Mind your own business. This is between your mom and dad who are both adults. Do what you need to for your own peace of mind but stay out of their relationship.
This is super family drama and u can feel any way u want to feel about ur mother’s actions but it is her and ur dad’s business that’s she’s cheating and ur not allowed to feel their feeling for them I know it sucks but there’s just really not much u can do here other than let ur mother know how u feel about what she’s doing and its wrong and u don’t agree!
I don’t think she’s wrong. She doesn’t want to carry on anymore and she did ask 4 a divorce…if she feels so then why force her 2 stay
It sounds like ur mom has made it clear before that she wanted out but for whatever their reasons are she hasn’t left yet. Your parents haven’t been together for what sounds like a long time but if ypur mom is going to keep cheating she needs to just leave and stop hurting e everyone
Same boat right now. Almost exactly. I feel like my dad already knows and he’s going with “it’s cheaper to keep her”. Sadly it’s what it’s become to be. I’m an adult and out of the house so she does her thing and I just keep the peace with my dad.
I feel you should stay out of married people business… If dad really doesn’t have anything to say about her cheating then you shouldn’t either… The situation really has nothing to do with you or your sister that’s between them
You don’t do anything, it’s their business. Let your mom and dad work it out.
1 Like
All these defensive, snarky remarks are making it clear who has cheated in their own marriage.
She’s their child. If you’ve never been in this situation then you really can’t understand. It’s awful on/for the children.
OP- I’m sorry you’re going through this 
1 Like
Unfortunately not your business- your dad knows what is going on- if he wants to put up with it there’s nothing you can do or say. Whatever you do, don’t discuss this with either of them- it’s not your place honestly- and it can only make it worse. Your dad doesn’t need to be told he’s foolish and your mom already knows she’s wrong. Let them figure it out.
What your mother is doing on her own personal time shouldn’t affect how you or anyone else feels about her other than your dad. You’re her child not her friend and if you distanced yourself from her and something happened to her, how would you feel? Sad and full of regrets. She’s grown and makes her own choices as well as your dad.
If your mother wants a divorce bad enough she can get one with no participation from your father. It’s called a no fault divorce. No grounds need to be given. She will just have to serve him the papers. Now if she wants the assets divided between them then it is a more complicated process.
Not condoning cheating but your mom has literally asked for a divorce and your dad refuses… honestly just sounds like your dad is playing victim and dragging you and your sister into it to get you on his side. And the passcode thing honestly I wouldn’t let my daughter have it either she doesn’t need to be in my phone 
I think you should find some business or a marriage of your own. You don’t know what your parents have been through. Perhaps what your mom is doing is some sort of get back. Maybe it’s an arrangement that’s between your parents. Either way it’s NOT YOUR BUSINESS.
Honestly, it’s not your marriage. Your parents are in enough turmoil right now, trying to figure things out and don’t need you poking around stirring up even more drama.
1 Like
She is having her cake and eating it too! Obviously she raised your girls with more morals then she has! You need to tell her that your not gonna stand by and watch as she takes advantage of the situation. She is your mom and its gonna hurt but you may have to distance yourself from her. You dad needs to put his big boys pants on and put a stop to her using him. But in the end all you can do is talk to them and then make the decision that is best for you. If it hurts you that much distance yourself so that you are not involved or aware.
Wow y’all sound really bratty. Stay out of their marriage and remember those are your parents. You’re grown, let them live their life. I doubt you’d want them interfering in your life and tattling on you.
Sounds like they are more than old enough to handle their own business and you kids are grown or darn nearly grown yourselves and you should mind your own business and let them mind their own, if you feel the need to act differently toward your mom that’s your choice and leave them to theirs.
Your mom deserves to be happy. Tell her that you love her no matter what and will not hold it against her if she divorces your dad.
Just ask your dad if your wasting time being upset with her.
If he doesn’t care, u might as well not care either
I would leave it be. As much as you want to “fix things” some things are not meant to be fixed. Or they have an arrangement. Just let it alone
1 Like
I get that you guys are hurt but to be going behind your mom is wild . The only person that should be snooping like that is your dad. I’m sorry y’all going through this though I believe cheating is trash and it does hurt the family but I wouldn’t meddle in their marriage tho
You guys are grown . It’s between your mum and dad . He’s obviously fully aware and chooses to stay . Yes she shouldn’t cheat but it’s their lessons to learn and obviously neither are happy
Honestly it’s best to stay out of it. Me and my sister was pretty much in the same situation. My mother cheated on my step-dad for 4 years. ( we knew what was going on but too afraid to tell our step-dad because he was abusive towards her while we were children) anyways they would always try to stick me and my sister in the situation especially after he found and the truth and she left the family home. After 2-3 years struggling with both of them, my mother decided to cut ties with me and my sister. Trust me, it is better to stay out it.
That’s all your mom and what she dose would you want her going threw your phone and what not telling your s.o everything you say or do I doubt you know everything about your parents relationship because we might fight in front of our kids from time to time but there is always more then what people see and even what will be said to people because in all reality anyone’s relationship is no ones business but their own unless they ask for help or advice just stay out because prying and pushing your way in the middle is not what you want trust me one of them are going to hold it against you …
Cheating is so fucking disgusting and cheaters deserve to be outed. Personally, I’d cut off all contact with mom simply for that. If he is aware of the situation then that’s all you can do. Let them deal with it and choose if you want to continue to have your mom in your life/ect. Hope she gets her karma tho
I was in this exact situation. Genuinely feels like I’m reading my story lol my parents are happily divorced now and with other people. My mom was cheating and I knew about it but didn’t tell my dad until he asked me. I kept out of it but I refused to lie to my dad when he asked 
My son once told me if I ever cheat on dad he would never forgive me and to him I would be a whore,
He doesn’t know what kind of hell I was going through with his dad, he only saw what he wanted, I wasn’t having an affair, but worked long hours as a nurse, while my husband gambled his paycheck away. You may not see what’s happening, just be there , and don’t point fingers or assume that something is wrong. If I was having an affair, it’s my business, and my life since my children are adults , they should be minding their own life.
1 Like
I get it hurts
But as you have said they are unhappy so there already means they shouldn’t be together
The fact they are is their business and what happens is their business
Yes your mom shouldn’t be cheating it’s not ok even in a unhappy marriage
She needs to grow up and leave but that being said it’s not your place to fix or what not
Yea you can be sad and upset but do you do things that upsets your parents I bet you do because we all do have they stopped loving you no
Talk to your mom and let her know your feeling
The biggest issue the human population has is communication when people don’t communicate to each other things than nothing gets put out or solved or understood
Yikes. I’m sorry people aren’t being so nice in the comments. I know it breaks your heart and it’s hard to sit back and watch it happen. Your dad probably already knows but is choosing to ignore it. She has already admitted once to cheating and said she wanted a divorce. I’d talk to your dad about how he feels about it. If he knows she is up to no good, he has a few choices he can make. a) try to fix their marriage, ask him to talk to your mom about couples counseling. If she refuses… that’s her choosing whatever 2nd life she’s created over their marriage. Or b) ignore the fact she is doing sketchey things and act like it’s not happening, Then maybe ask him for advice on how you can deal with that choice Bc it hurts you to stand by and watch her do that to him and the family. Or c) he wants to do something about it, you should get him to hire a private investigator. I guess it depends on the state you live in, but Especially With him making more money than her, he would have to pay alimony to keep her up. But if he hired a private investigator who could catch and prove her cheating on him, he wouldn’t have to pay alimony Bc she chose to be unfaithful. He might be afraid to file for divorce Bc he doesn’t want to divide or “mess up the family.” But speaking from experience, it was such a better environment for our family when my mom left my dad instead of staying and continuing to be a doormat for the sake of “keeping the family together”. Im sorry this is hurting you. Just find a good time when you and your dad can sit down without distractions and talk honestly about this situation. Even if he doesn’t want to talk about details, let him know his options and how each makes the family feel. Maybe if you and your sister both feel the same way, y’all 3 could sit down together.
1 Like
My goodness. I’m a product of divorced parents and it was hard. I was also 13. I can understand how it’d be hard to see your parents that have been together forever acting in such a manner, even as an adult. However, it’s their life, their decision and their choice. Obviously dad doesn’t mind it or he’d divorce her, make her pay some bills, etc. but if they’re in separate bedrooms and not affectionate how is this a surprise? Who knows what dad is doing in his own little world. They are probably swingers… 
Sorry but your mum is in the wrong maybe your dad stays because he really loves her and wants it to work but clearly it’s not the same for your mum. The fact that he “earns” more so should pay I don’t agree with atal it should be split fairly your dad still needs to live. I actually feel for your dad he doesn’t deserve this kind of treatment especially when he isn’t the person that cheated! X
It sounds like you just need to stay out of your parents business. Your dad will eventually move on if and when he is ready…. Your mom will reap what she is sewing. Theirs no need for you to insert yourself. Just love them both unconditionally and know that it’s their life and not yours. Parents won’t last forever and although you are holding grudges the reality is you really don’t know the true story… theirs always 3….
Firstly I have no clue why people would feel the need to laugh! Wtf is wrong with you all? And 2ndly I feel like no matter what ur mom and dad love u period! I think u should talk to your mom and tell her why you feel thee way you do but also don’t freaking gang up on her or get urself involved because obviously they have issues! You don’t know what ur dad has done or visa versa! Regardless of if she is cheating on him or not u said urself they basically have been done for a while why do you feel like you need to be involved. Break that cycle and triangle everyone has their dmons they have to face without their whole family picking sides
Your Mom doesn’t owe you an explanation!! What it comes down to is mind ya business!! Yes you are her child but no she doesn’t have to explain her actions to anybody but God and her husband.
Your dad knows, he isn’t dumb. He isn’t ready to deal with it. If it were me, I would have a Direct and honest conversation with my mom about happiness, honesty and Marriage ( that’s just who I am). I would be prepared to accept that she may leave if she isn’t happy. Which will be tough. At least she won’t be living a lie.
We all make choices;
You’re mom chooses to cheat. Which mean she’s capable of lying, manipulating, and causing pain to someone she loves(ed)
Now that you know she’s capable of such behaviors and choices, you’re more-than-likely subcontiously trying to distance yourself from her.
Cheaters are cowards, they’re weak, and they’re narcissistic…and when they’re called out they will blame anyone and everyone but themselves. In that regard you could add they have zero accountability for themself. They’re gaslighters (Google if you don’t know), and 99.99% of the time won’t even acknowledge the pain they’ve caused.
With that being said, it is their relationship, and not your place to interfere…but that doesn’t mean you have to like her as a person. Just because she’s your mom doesn’t give her a “free pass” to behave however she wants without consequences.
Clearly the intimacy has dried up in their relationship, no pun intended. However, that’s no excuse to hurt someone you once loved, and have children with. Be an adult, communicate your feelings, and work out some sort of arrangement if neither want to leave…this of course, is assuming the cheater is mature enough to see past their narcissism…which they generally aren’t.
I’m very sorry you find yourself in a position not of your choosing, and it’s okay to feel…anything you’re feeling. Just be there for your dad as best you can…cause when it’s all said and done you have to look at yourself in the mirror. Best of luck to you, your dad, and sister.
You have no idea what’s going on or the history. My advice is to talk to your mom and tell her you think you know what’s going on and see if you can A) listen to her B) remember it’s not your marriage
I had a similar situation with my parents. I let it go and when I went to my mom about my ex husbands infidelities she talked to me a little about how my dad did the same and so did she so they had an agreement. They decided on an open relationship it was 11 years at that time for me I had no clue. Maybe there’s something there y’all just can’t see it. I’m sorry for your situation tho it isn’t easy.
I see a lot of people think she should stay out but I thing she should be actively involved. But she needs to have a serious talk with her dad or take them to therapy.
Get busy with stuff that really concerns you…and that doesn’t include your mum’s cheating, or your dad’s lack of.
Stuff that concern’s you: Minding your business.
If you are an adult, just stay out of it. If she has been unhappy for a long time, but hasn’t gotten a divorce maybe it there is something more than what you think is going on.
It’s none of your business. Live your life and let your parents live theirs however they choose.
Maybe your dad likes that she does this 
it’s called cuckold. If his kids found out he would be embarrassed and ashamed in a different way than he would be when the wife does it. You’re an adult. They are adults. What goes on in their bedroom is their business.
This was my life, except it happened all throughout my childhood into adulthood. I kept secrets for my Mom that no child should have to carry. It’s absolutely the worst and unless your in the situation, no one will understand. Another member wrote about everyone sitting down and that’s EXACTLY what needs to happen.
If your parents choose to stay together after, you may need to cut ties for awhile for you to grow and figure things out from here.