Maybe my advice may see irrelevant, have you tried talking to a therapist for getting your dad treated ? He seems to be very defensive guy and he needs to chill a lot, i know you don't want to see his face anymore, but for a second think about him he's your father afterall and you wouldn't be here if it weren't for him and i do understand his abuse is too much for you people to handle and i get it you don't want to be around him, i suggest you refer him to a good therapist and there are few national helplines, you are free to stay away from him, but i kinda feel he needs therapy and guidance and yes he seems stubborn individual. But this is the Least thing you can do.