I’m so fucking tired of my mom’s manipulation

I don’t have a good relationship with my mom for several reasons. She cheated on my dad with the man she’s married to now. But she says she never did despite my dad having phone records with hundreds of calls between them. The man she married didn’t like me or my siblings but she stayed with him anyway. He was verbally, emotionally, and physically abusive to us. He’d call us names, curse us out for doing something small that was wrong, even handmade a paddle to hit us with to “keep us in line”. My mom pimped me and my sister out to him to get him to like us. She’s tell us to sit on his lap, I remember we gave him massages with oils while she just hung out. He’d stick his tongue in my ear as a game. He put his hands on my sister for “setting a glass down with too much attitude” in front of my mom’s work friends. Despite the fact that they told her what happened nothing happened. She also had to have limited contact with us. She had to sneak into our room just to talk to us. If she heard him in another room she’d quickly leave. There’s probably a lot of things I can’t even remember because I repressed it.

She wasn’t ever really a mom to me. When I was able to be free from her house she never did anything for me. She demanded child support from my dad for years even though I wasn’t living with her (and never used the money to take care of me). Never helped pay for anything, never offered to help my dad with college tuition. Nothing. She never even offers to come see me or have lunch. It was like Im not even her daughter.

I have a little brother from her and him. She constantly uses him to manipulate me and my siblings. She says we should come out and visit him, he would LOVE to see us. She’s even texted us from his phone (he’s 9) pretending to be him and tells us to come over. I don’t want to be in that fucking house. Especially not by myself. My heart hurts so much for my little brother, but it’s like that thing on an airplane, I can’t save others before I save myself. I feel like I’m powerless. I love him so much but I can’t stand being alone with her in that house. Especially if there’s a chance the man is around.

I’ve been able to shrug off most of the manipulation. I wouldn’t have a relationship with her if it weren’t for my little brother. I don’t know how to fake it like her. I don’t not want to have a relationship with my brother because he’s going to need me when he realize how toxic that environment is. But I’ve never been able to set boundaries. I feel like it’s obvious that I don’t want to be there but she always pushes it.

I wish I knew what to do