‼️sensitive subject, TW child play ‼️

Ok this is going to be extremely hard to explain fully. Let me start from the beginning. I dated a guy (C) for about 2 years. In those two years I had gotten beaten 4 times, he’s been arrested 2 times for this. He was a very odd person, and the longer I was with him the more I found out. At the end of our relationship I found out some pretty horrible things that then lead to us ending our relationship. I knew he was hiding something from me, he never really fully “got off” during sex. I knew he was missing something. Come to find out he has a fetish for “littles” I had found an old photo gallery in his phone that included his ex wife in onesies, diapers, and binkies. I confronted him about it and he basically said he’s attracted to little kids. I really didn’t understand how, I was very confused and really worried for his children. He then proceeded to ask ME to wear diapers etc. HARD NO. So whatever I ended things. Skip to current time, he’s now dating my bfs baby mother. FUCKING INSANE. I’m extremely upset. He was out of my life for good and now he’s back in it. once he comes along my bf is no longer allowed to see his daughter, shes taking him to court (it’s a good thing) but she’s asking for sole decision making and 80% of time. Completely unfair as my bf is way more stable and in my opinion a better parent. Mind you they’ve been doing full 50/50 for a year now. But now we have to worry about my ex WHOS ATTRACTED to children around his daughter. Im so upset and have no idea what to do. I’ve also been told by my bfs bb mamma old friend (who has heard him talking about this child play) that she’s now having to wear diapers and talk like a child when they have sex. Please tell me this isn’t ok.