Idk what to do

Ok I’m gonna try to make this make sense in the shortest way possible. My dad is a drunk. A very abusive drunk. My mom just got their divorce finalized a little over a year ago. My dad is a completely different person when he’s drunk. He’s has told me I’m a worthless cunt, cheated on, peed on, choked, and beat my mom. I’ve had to slap him off of her. My cousin and I are 18. She has been my best friend my whole life. We’ll call her L. We’re more like sisters. I have a very strong hatred toward alcohol and I assume it’s because of my dad. My sister is also a drunk. L has recently started drinking. Even the same “type” of alcohol my dad drinks. And for some reason it has crushed me. Idk why. I haven’t told her how I feel because I feel it’s wrong of me because it’s completely her choice. But idk what to about how I feel. Idk what I’m even looking for in making this post. I just need to get this off my chest I guess.