How do you know when it's time to end a relationship?

I have been married for 27yrs. We started dating when I was 16. I have been with my husband for more than half my life, and we have four kids. Being married young, we have gone through many struggles, including cheating on one another. The only thing is, I didn’t know about his infidelity until I confessed mine. The relationship has been toxic for many years. Our kids even tell us we should divorce; our oldest is in college. We tried counseling after my affair came out. At that time, he only cared about my situation and wasn’t willing to accept accountability for his wrongdoing, and all focus was on me. We got through that rough patch and moved out of state, away from where my infidelity occurred, away from our family, and left our friends. Our kids were miserable, so we moved back closer to family. Life for them has never been the same. I have guilt every single day. My husband isn’t very active in their lives, and my kids will say their dad never does things with them. He and I don’t have date nights; he sits in a separate room all the time, doesn’t sit down with us at the dinner table, and is on his PlayStation most of the time. When I ask him to sit with me, he tells me he doesn’t like watching or doesn’t like my shows. I have said we could find something together we both enjoy. He still drifts off to his PS4. He’s either playing that or watching videos of people playing video games. I feel like I am second to a PlayStation! There’s no intimacy or affection. I feel myself becoming resentful. He stays up sometimes till 5:30 am on the weekends playing his game. Then he wonders why I don’t want to be intimate with him. I am feeling no emotional connection. Then, last weekend, I decided to rearrange the furniture. He flipped out when I unplugged his PlayStation because he said since I didn’t turn it off all the way, I could have corrupted the files. He got nasty. He told me he played his game so much because he can avoid me that way and that he doesn’t like me. He told me he was only here for the kids. Two of our kids heard him. We haven’t spoken in over a week. I am hurt and refuse to just give in. We live in a state with no family. I don’t have any friends here (nor do I have any back home since he made me block everyone after my affair). Two nights ago, he was yelling at the PlayStation at 2:30 am. We were all sleeping, and I texted him and asked him “to please shut the F up because people were sleeping.” Yes, I know it was rude for me to talk to him that way, but he has no care when he’s on his game, and he’s constantly yelling at all hours on TV. When he came to bed at 5:30 am, I was asleep at first. He shined his phone flashlight in my eyes and said, “how about that, wake up, wake up, you high maintenance b-word.” I pretended to stay asleep. He calls me high maintenance because he says I am too needy because I want him to sit with me, want us to hold hands, want us to have conversations, want to feel appreciated, and if he doesn’t do those things, he thinks I will cheat again. Let me remind you; he has also created… he admitted having intimate moments with five different people earlier in our marriage. He says my cheating was different because he never had actual sex; he said he tried but was too drunk to perform and that he knew the person I had an affair with. I don’t want to sound as if I condone cheating, I don’t. I know it was wrong, and I have guilt every day for my actions on how they affected my kids. However, at the time I cheated, my husband was very mentally and emotionally abusive. The person I had an affair with built me up, made me feel smart instead of dumb, made me feel like I was deserving of happiness. Anyway, when is enough? Why do I continue to stay? Last night, my husband came upstairs and told me I looked pretty and wondered where I was going. Mind you, the night before, he shined the flashlight in my eyes and called me a high maintenance b word. I feel like I live with Jeckyl and Hyde sometimes. I didn’t respond to him and left to take my kids out to dinner. We have hardly spoken in a week at this point. I know if my kids were in a relationship like this, I would tell them to RUN! So why do I stay??