I don't know the right answer for you, but I know that *I* would be more likely to hold off on an official wedding & tying ourselves together legally if I was seeing this kind of behavior.
Him pitching in to help our more while you were sick is awesome, but in my book that's what is SUPPOSED to happen, so it wouldn't earn any bonus points. It certainly wouldn't make me more forgiving toward his drinking.
Lapses DO happen for some, but they aren't a built-in definite part of recovery. There's also no guarantee how long this "lapse" may last, right? I've heard stories that go from a 1-night mistake to years of continued drinking.
Was he IN recovery before he lapsed, or just "not drinking"?