Sue, It seems like he's throwing just enough crumbs your way to keep you appeased ... the occasional family dinner or outings, etc. Yet he keeps living his own life. Damn the torpedoes, full speed ahead!
Good for you for letting him know you were aware of what he was doing. You said he was nice/talking after that. Guess he was trying to smooth things over. Were you nice/talking back?
What do you think he'll do when BIL and SIL come to visit? Will he stay home or go out and party with his friends?