Hmm. Well, he sounds like he has anxiety, so that diagnosis makes sense. I am not a medical professional though so I don't know, I am just basing it off what you said in your post.
A lot of us anxious people try to drink to self-medicate, and when we take the drinking away the anxious or obsessive behavior doesn't necessarily stop. Sometimes it even gets worse for awhile before it gets better.
Good for you for setting boundaries and sticking to them.