I just wanted to say that I think your attitude towards the whole situation and the way your are putting your children first is admirable. You seems to have a really level head about the whole thing.
As for if he drinks, if it were me, i would probably remove yourself and your girls from the situation as they are probably not going to be having a nice time/rebuilding their relationship with him if he is under the influence. I don't think the two go hand in hand.