My personal red flag popped out: y'all were drinking. Exactly how much alcohol did he have? I realize alcohol doesn't create grievances, but it loosens the tongue so people feel entitled to gripe.
You said "at some point," he started cricicizing you-- at what point exactly? It seems to me that something that you or someone said triggered his "starting to criticize," and that because of the alcohol, he said something that he would have normally stuffed. Can you remember what y'all were talking about when he started in on you?
Was the other guy talking about making a bunch of money at work? They were getting ready to take a trip? Build a house? Something about the kids?
I agree that you need to make it clear he cannot diss you in front of others, but I'm really curious about exactly WHAT ticked him off enough to start sniping.
