Hi, Hopeful--so sorry. I am also in the situation where I can't always tell if AH has been drinking, although he has not had a successful period of sobriety.
My thought is this--if you ask, he's going to say he hasn't been drinking. And that will mean (a) he hasn't, but you're going to go nuts wondering if he's telling the truth, or (b) he has, and you're going to go nuts wondering if he's telling the truth. What a spot, eh?
You've been through bad already with him. Sit down in the most objective mood that you can and get out a piece of paper. Write down the behaviors that are below your bottom line--the behaviors that are observable, not that you have to count on him to confirm. Really decide for yourself if you can get out for good if he crosses that line. Then become a watchful observer.
This probably sounds cold--I'm typing quickly because I'm on my way out the door for work. But my heart sank reading your post because I can physically feel that no-win situation. Best wishes.