You might look at the alanon forum on SR. They can give more specific advice to you. From an alcoholic/addict perspective, I can tell you that he probably wont get better until he hits bottom. That's just the way it is for us. Different people have different levels of pain they can withstand. He can't get better FOR you or your daughter, he was to want it for HIMSELF.
With that in mind, you leaving him might just be the 'last straw' he needs to see what he's been doing wrong and change his ways. As long as he is forgiven and welcomed back, there is no reason to change.
Good luck to you in your struggles. We'll always be here for ya.