skwgtb.....don't think that you just have to walk on eggshells or just tolerate his bad moods. Especially, you don't have to be the constant recipient of his bad moods.
You might be right...he might be getting ready for a relapse or he might be sipping on the side or whatever....
Have you expressed your feelings to him (I am surmising that you have).
Do you have any boundaries for yourself in place---what you will do if he continues to be nasty to you...or if he drinks...or hooks up with the ex.....
Bottom line...he is going to do what he wants to do, anyway. The question becomes--what are you going to do.
Don't ever h and your power over to someone else.....
dndylion