My sister is an alcoholic and was driving my (quite small) nephew around drunk to get more booze in the middle of the night and taking him to school in the morning still drunk from the night before and shit.
Hey, mess yourself up - I'm not as arsed about that as I am if you're going to kill my nephew in a heinous car accident. Not that I want anything to happen to her either but that was the final thing for me, maybe.
I ended up having to really limit contact. I didn't cut ties with her but I really made it "arms length" as one would say, you know? Instead of going around we texted and I stopped calling really mostly at all. Now we only speak a few times a month because I know that it's just going to center around problems -- finances, mental health, drug & alcohol related shit -- it all ties together right? But I can't let her problems become my problems either and that's how it was.
You said this person is close enough to you to hit you and such? Someone you live with?
It's different for their friends because their friends dont <fill in the blank> hit people when they are drunk, drive when they're drunk, have problems with their family when they're drinking, have financial problems due to their drinking, get into fights when they're drinking, fall into a soggy wet mess of crying when they're drinking... make a list of whatever it is for this person that makes it different. *I* dont know what that is but you do.
I'm sorry you're in this position. I'm certainly not advocating for you to bail out on this person. Only you know your situation and what is best for you (though allowing someone to hit you does make that look more like you should leave, not less). I hope you can make her see that this is a problem - and fast.