advice please! POSSIBLE TW!

Going to try and keep this short, but basically the father of my child has been accused of rape/sexual harassment more than once. I didn't know about these things until after my relationship ended. The girl who is accusing him of rape is his younger (underage) sister. She's tried to get help but their mother treated her badly and told her it wasn't anything bad and that she just needs to stay quiet about it. The sister told me this herself after we broke up. He also dated a girl who wanted to wait until marriage and when she wouldn't have sex with him he forced her to give him head. She admitted to me that she was very afraid of him throughout the whole relationship. While we were dating he also got fired from a job for making sexual comments to girls there and wouldn't stop making comments even after they asked him to stop. I learnt this from my sisters friend who knew him from work.

He wants to try and get custody of our daughter but I'm scared of what he might do to her. Again, other than him getting fired from the one job, his sister being raped and him forcing his ex to give him head have never been reported and I know it's not my place to say anything. I just don't know what to do. The first time I had sex with him I kept telling him no and he kept on until I gave in but since I finally agreed I didn't consider it rape or anything. He also would sometimes be very rough during sex, sometimes biting me until I was bleeding, hitting me, spitting, and leaving bruises. I never considered it abuse and tried to accept that it's just his sexual preferences but now that I'm out of the relationship I know it wasn't okay if I wasn't comfortable with it and expressed that to him. I'm mainly just terrified of what he might do to my daughter if he is granted any sort of custody.