Alcoholics lie, that is what they do. If he wanted to be truthfull he would have told you that he drank, he chose not to. "A's" think they are so clever, and the rest of us are such dummies, they always get caught, over and over again.
To me, there is nothing to discuss.
I agree, watch his actions, decide what you are going to do if he continues to drink.
Work on your own recovery, he is an adult, let him figure out what he needs and wants to do.
This is your life, what do you want from it? There is no second chance, no dress rehersal, I'd reevalute my situation and go from there.