Majoru Oakheart: You DO deserve an apology for his tantrum. You won't get one, so I'll apologize on his behalf. I'm sorry that guy was a jerk to you and your friends. You deserve better.
You can't control other people. You can only control yourself. Stop worrying about this guy -- don't give him any of your mental energy. Instead, be the best damn Majoru Oakheart you can be. Part of being awesome means being patient, forgiving, and understanding. BUT another part of being awesome means not putting up with any crap, at all.
The best thing you can do when someone is getting upset, angry, irrational, and "believing what they want to believe," is to counter it with calm, patience, reasonableness, and honesty. Just tell that everyone you DM for, what is and isn't acceptable at your table, and stand by that. Don't single out this guy -- he's not your problem, he's his own problem (and his girlfriend's problem). YOU be the Buddha DM. The friends you are worried about losing? Just keep in touch with them, hang out with them, invite them to your campaigns, etc. If they ditch you, they weren't worth being friends with, anyway. YOU be as awesome as you can be and the rest will fall into place.