I don't mean this to sound insensitive, but don't let him pull you down. Alcoholics are not going to seek help because someone else wants them too. He will only seek help when he feels there is something else worth living for other than alcohol. Maybe you should talk about moving out. You don't want to spend your whole life with someone who promises you they get better, but won't. Maybe when he realizes he DOES have something to lose, a switch will go off to get help.
I'm so sorry you have to go through this. *hugs*