Somehow I think that the part about your fiancee giving you permission points to the heart of the problem. Not because he's a bad guy or anything but unless you're doing this for yourself you're never going to really be free of the addiction. Sobriety can't be conditional on someone else's wishes because it doesn't really cure anything; it's gotta come from within yourself.
It's still great that you quit. Try to get to the point where you're doing it for yourself first though, and it'll be way easier to manage situations like this.