He sounds like a complete mess. He may have a plausible reason (delayed reaction to his divorce) but the drinking is his way of coping. El RED FLAGO! That will be his pattern... something stressful? Take a drink.. or two or 12. Is that how you coped after your divorce? Probably not.
He is treating you shabbily. And immaturely. Oh and he relapsed, reason enough to keep your distance until he gets his head straight or before long he will be blaming you for his drinking.. the 'lighten up' comment hints at that most likely happening.
Maybe step away until you he finds sobriety again.