How to react to a parent that is a major alcoholic?

My dads mom just died and everything bad has been happening and he just got more worse and more violent. And I always yell at him when he yells at my mother, brother or friends. He will just yell for no reason. He drinks from 4:00 am til the time he goes to bed which is around 11:00 pm.How do I react to it without going to one of those classes for an alcoholic parent?