I think it is great that you want to break up with "drunk" boyfriend. I would do just that; when you are with him and he starts drinking "too much" for you, then leave. Let him know, before you go out, that that is what you are going to do; that he can have a "couple" drinks but after that and you will warn him once you will be leaving if he has another and then do that. Eventually he will either realize he is messing things up and work on fixing them or he'll be someone you don't want to hook up with because he refuses to respect you and/or anyone else's needs; is not "grown up enough" for an adult relationship.