I’ve always had to deal with them yelling and fighting all of the time. It gets worse when they drink which is most days. I don’t live there anymore but I was staying there for a few nights. Things got out of hand and they got into a huge fight, too much to retell.. but summary of the story is my dad punched her through the cup she was holding and it when into broke into her face and knocked her down. I didn’t know what to do so I called the police. I always feel guilty for doing this but idk what else I can do. 
Sometimes I really worry that he might kill her someday 
I feel so depressed it’s hard to stop thinking about it