Is my stepchild ruining my marriage?!

I need stepchild advice!!

I feel like my husbands son is ruining our marriage. We’ve been married for 5 years, he’s got 1 son (20 now) and I’ve got 3 boys (17,15 & 13) and we together have a 2 year old. My husband has always been a single dad, he moved him and his son from CA to be closer to his mother and sister. His son choose to go back to CA and stay with his half sister to finish school. He ended up dropping out and getting his GED. His sister let him do whatever he wanted and even partied with him. His dad being one to not believe it after I told him countless times quit sending the sister $1000 a month he’s not getting any of it for his use. His dad was still buying clothes and care packages for him. The sister was constantly drunk or high and supporting her meth boyfriend and all his child support. Eventually when we got married I said that will stop, his son is old enough to work let him work and support himself. He is 20, very lazy and spoiled (everything is handed to him!!) he’s never been taught to work for anything. He finally found out the few years he’s sent his son money wasn’t going to the son. His son moved out into his gfs.
The money did stop but that wasn’t the main problem, the problem is his son is disrespectful to his dad and then turns it into a joke trying to manipulate him. He doesn’t ever call/text his dad unless he wants something. It saddens me. I’ve watched his dad cry and be upset his son is across country and not living with us for the fact we have a family and he’s no part of it.
We had plans to visit last year but due to covid we didn’t go. His son was sooo overly excited for us when we made plans, then when we told him we wasn’t coming he said he had plans to tell his dad he got his gf pregnant. He was only 19, living with the gf, just got his GED and no job. Actually he got a job a week before he told his dad and the baby was a boy and she’s due the next month. Waits 8 months to tell his dad!! He knew the entire time!!
His son has always been disrespectful to me, I don’t put up with any child disrespecting a adult and when I’m around I put him in his place. I think children should have manners, discipline and his sons not once showed any of that. He horse plays when we go out to eat, yanks my phone from me for taking pictures on Xmas morning, I’m driving and he puts my husband who’s next to me in a choke hold, he’s walked out of the house cussing because he’s not gotten his way and takes off wherever. He’s trashed me to my husbands family. There’s been so many situations, I’ve never gotten a apology for anything!
My boys are not perfect but his son is on a whole different level. My kids are still on school, very smart academically, very respectful, well mannered. They know I don’t tolerate any negative or absurd behavior.
My husband pretty much let’s his son do what he does. He surely doesn’t punish his son. We’ve been round and round about this.
So after telling his dad he’s gonna be a dad he gives his dad an Amazon list of items priced of $100 or more and wanted him to buy everything off the list. At that time we had a baby and I was just off work for medical issues and there was no way we could afford it. I had to step in because me and my husband are suppose to be a team and we share our money on a joint account. He bought his grand baby a car seat/stroller combo that was $400. No big deal that’s his grandchild. But do you know that gift tag said my name on it too and he called his dad and thanked him and not me?
His son never came to visit after his dad and I had our baby girl, she will be 3 and his baby will be 1. We’ve offered to pay for the airfare like we always have and he still has no interest in meeting his sister.
So we are going to visit next month and my stress level is so high because of how his son is. He works at a fast food place, great he’s got a job! He’s been offered a damn good job with his uncle in a factory and turned them down bc he would get drug tested. He says the fast food place is where it’s at. He stays high bc he thinks he’s a thug. Lives with his gf and her mom and they smoke around that baby and fight all the time. I’m dreading this vacation as his son has never apologized for when he did come out to visit for being so disrespectful and he’s never showed no interest in his sister. So it’s like he needs us to visit bc he has a baby but couldn’t come when we had his sister. It’s all about him and only him. He’s never cared for my boys and us going to visit is going to be me and my boys just sitting in the hotel. (He’s already called his dad and made plans for them to do without me). We are to be a family, I’ve married his dad, we have a baby together! Am I over reacting here or what? I need advice, I need to talk to someone because it’s getting worse and I just feel like his son is ruining our marriage. I’ve tried to talk to my husband and he says I’m just being negative and always takes his son side! Everything was fine when we got together before he moved to CA and he moved out there. Others have said his son is in the wrong as well and needs to grow up!
Please help me out!!

I feel like you are right. He needs to grow up, especially when he has his own child now. It’s hard though, parents in general never really see how their child truly is because… well it’s their kid and they couldn’t do any wrong. Are your sons going with it is it just your daughter you have together? Either way, I would sit with your husband and talk about it. Calmly. Tell him you feel hurt because the plans that have been made don’t include you & you thought this was a family trip. If he still isn’t getting it then I would just tell him you’ll make plans with your children then, or even by yourself. There’s no point in staying at a hotel by yourself. Research what there is by the area you’re going too & pick some. Try to have fun! As for things in general, I think your husband just gets happy to be involved regardless of what it is. Sending money, excluding you. He really needs to sit down & realize what he’s doing.