Thanks for your replies.

I just don't understand why I snapped last night. When DS was 10-11 months he went through a crappy, crappy period of sleep. He was up every 2-3 hours every night for well over a month, and he was also difficult to get back down each time he woke. I had a few moments where I cried, but I never snapped at him like that. Now that he's sleeping better usually I'm finding it harder to deal when he doesn't .

It is comforting to know I'm not the only one who has been through it. I don't feel like quite as much of a monster.