My dad would occasionally tell us stories from his childhood. Stuff like his dad grabbing him by the shirt collar and repeatedly punching him in the face. When I was a kid it was just another story. When I got old enough to actually understand what he was talking about it was like, "God damn. No wonder you're like this."
I couldn't help but feel sorry for him. It didn't undo anything he did but it did help me hate him less.
I think I'm really fortunate that my dad somehow realized he completely fucked up and made an effort to repair his relationship with his kids. We're on good terms now and he's a way better Grandpa than he was a father. I know a lot of people go through their whole lives only getting to see the worst side of their parents. My dad included.
You are not alone. Your parents do not define your value. Despite their best or worst efforts, they do not ultimately get to decide what kind of person you will be.