While I can certainly sympathize with Liz for losing patience with David's bigoted and misguided views, maybe breaking up with him wasn't the best move. Although I realize she didn't actually break up with him, but rather told him to think about matters and not talk to her until he saw the error of his ways. But it's natural for David to feel she's broken up with him, especially since she probably will, when he persists.
His strong reaction was a surprise though, and he seems to have pitched headlng into a depression. Not a good sign - and my earlier suspicion about him repressing gay urges suddenly jumped up again. But I think he could react like this just from feeling rejected, since he obviosly has issues about that. Eg how he worried about Randy facing rejection if people thought he was gay. (or is that David projecting his own fears. hmm now I'm all confused)