This is going to be long so please bear with me. I have so much resentment towards my dad. He has been such a shitty father my entire life, from cheating on my mom when I was little, to going to prison for drugs for my entire childhood, to verbally abusing me until I moved out.

Last August my mom went to the beach for vacation, while she was at the beach my best friend stayed at my dad's house the whole week and no one knew. My mom watched on cameras (that my dad had around the house) my friend and him holding hands, kissing and hugging throughout the house.

When my mom got back from the beach she tried to talk to him about it but instead he got really drunk and passed out (cause he knew he had messed up I guess) so when he passed out my mom went through his phone and found all kinds of messages between him and my friend.

This same night my friend was at my mom's house with me and we were in the sunroom watching a movie. My mom came in, crying and had my dad's phone in her hand. She stormed off after grabbing her phone and her ciggies and I told my friend to go after her to see what was wrong (at the time I didn't know anything was going on). She followed my mom and my mom told her to fuck off.

When my friend came back into the sunroom she immediately started crying and told me that she had been talking to my dad and while my mom was gone they kissed, went to a casino, and then slept in the same bed during the week.

The following months my mom tried sooooooo hard to do things for my dad to try to work things out and make everything normal again. Of course I told my friend she was awful and I didn't want anything to do with her. But she kept talking to my dad, they were going behind my mom's back to see each other and my mom just kept trying to make things work because she had given her whole life up for him. Even when he went to prison she raised his son and me.

I had talked to my dad a couple times about how stupid and awful the things he was doing were. And how mom didn't deserve it. All he could say to me was "why does no one care about what I want?" He honestly thought that he could have them both. He still would not speak of any of it with my mom. Anytime she brought it up they would argue and she would end up crying and getting no where with the closure.

On Christmas 2019 he beat the shit out of my mom because they got into a heated argument and they had both been drinking. I went and got her that night and she stayed with me for a week. The worse part about all of it was watching her every night cry herself to sleep because she had done everything for him and he couldn't respect her enough to just leave. She said the only memory she will ever have of him anymore was of him choking her telling her he hated her and wished she would die.

Fast forward to about the middle of January, my friend has moved in with my dad. I haven't spoke to my dad but he doesn't seem to care about talking to me either. I talked to his mom and she said that he wants to fix things and have a relationship with me. But I hate him. I want absolutely nothing to do with him. Even if I forgave him for what's done to me, I could never forgive him for what he did to my mom.

This whole situation has been so hard on me, I have so much pent up anger towards him and I know I'm gonna have to talk to him eventually. Would I be wrong if I never spoke to him again? Told him I wanted nothing to do with him? No matter how much he thinks he's a changed man and a better person I don't think I can ever imagine him being in my life again.

Sorry again this is so long, it's just so much to get out. I will answer any questions.
Tl;dr: my dad is dating my best friend, he beat my mom on Christmas and verbally abused me my whole life after missing my childhood by being in prison.
EDIT: I have dropped "my friend". Almost immediately after me finding out.