Stepping away because of her toxic relationship

Hello guys! since this boards helped me so much, I wanted to share something with you guys to see whether I might be overreacting or is my friend just too blind to see the reality. This is a bit of a long story so please bear with me, this is also about a close friend. So my friend has been going out with this guy for about a year they met because she was fooling around with this guy’s cousin and when they ended he started hitting on her, my advice to her was to stop talking to both cause I didn’t think it was right for her to be intimate with his cousin and then with the new guy (the two guys were close at the time). Behind my back she still started fooling with the new guy and only told me after they had had sex. The guy, at first, seem okay which is why I didn’t really keep bugging her about it plus I am the queen of toxic so I was afraid that if I said something she would just point out the fact that I also suck at choosing guys. Anyway, when they started dating she has two close friends (me and another girl) but she had issues with the other girl and they eventually stopped talking and her new bf was one of the reasons. I till didn’t pay much attention to it but she did started spending a lot more time with the new guy and we barely saw each other to the point that she was barely around when my on-and-off relationship finally ended. As she started spending all her time with him I used to tell her that it was okay to spend time together but it was not okay to be excessive and then she started failing classes in school and not really caring about things. When this guys tried to get with her the first time he lied about how he wanted help going back to school and then never mentioned again after they were finally together. On her birthday they had an argument about something and he called me and had me on the phone for over an hour talking about how she should behave and about things she shouldn’t do while she was in a relationship; his long list included not hanging out with guy friends or something of that sort and I was like WTF the whole time, that night she came to sleep over at my place and I told her that regardless of what could happen between them he should not be calling me to talk shit about her, which is basically what he did, thinking that I would take his side, not only did he call me but his mother called her to tell her that “a woman that respects herself should not have guy friends”, the following weekend they had made up and she has her birthday celebration (she is 21) and right there in front of all her friends and her mom they had a disagreement and he started ignoring her, in fact, he went to another side of the place with two friend he had invited and she stayed with us the rest of the night (most of us srtared really disliking him then) as they proceeded to just ignore each other the rest of the night. After this, and her mother telling her how wrong the whole thing was, she still took him back with promises of changing and him crying. He has recently gone back to church and she explained to him that she wanted to practice abstinence and he seemed to be okay with it at first but afterwards he was like “im already used to having sex with you so you can’t take that away from me you have to think about me FIRST” as in put me before whatever you believe in. Recently they had another fallout and we started hanging out like once a week again and one of the nights they were supposed to meet afterwards but he had not texted her so she calls him still been in my apartment (she lives 5 mins away and he spends all his time at her house) and I heard him say to her with a attitude “you should’ve been home a long time ago”, a day or two after I was speaking to her on the phone and he kept calling her so she shoot him a text saying “did you get to my house yet?” which he ignored and kept calling when she got to her place I was still on the phone and I clearly herd him again in a crazy tone of voice “I’m calling you, why are you not answering?” after that they had an argument and he again demanded to be put first, he wants to be the center of everything. And this is not all the things that they’ve been trough, however the other day my friend had the courage to break up with him and the next day he showed up at her house crying and rang her doorbell for over an hour and called her and texted her and guess what she did? she took him back and, not only that but in the two days they were brooke up for he called her mom (whom I close to) and told her that she wasn’t spending time with him cause she was always either with me or on the phone with me which is not true cause I have a full time, a part time and I am a full time student so I definitely don’t have a crazy amount of time to spend with her, we did communicate often enough I guess… So after all this happened I decided to take a step back and spoke to her about it, I just rather not be involved at all cause this guy talks about everyone, she was upset and played the whole when you were in messy relationships I was there for you which I am not denying but non of they guys I’ve been with have been controlling or have dared to talk sh*t about my friends because I would’ve never permitted that disrespect, as well as the fact that she had a moment of clarity and has consciously decided not to accept it, in my relationships I was very confused and that never really happened. I’m very upset about the whole thing as well but I really don’t think there is anything I can do since her decision was to keep at it. Sorry for the long post, I hope you guys can give me some insight.