Bottom line, he is NEVER going to admit to drinking... even if you caught him with the bottle turned up! I would stop asking him and stop "wondering" where he is going in the night because you KNOW he is lying about it all. I agree with Trailmix and have read her replies to many folks that "the Devil and the Angel are one in the same"... there is just the guy who drinks.
I am sorry you are going through this and am so sorry to see the physical and psychological effect it is having on you. Please focus on yourself and your kids... they need you now and will need you more as the roller-coaster ride continues.