If the other poster was the angel on your shoulder, I'll play the devil.
If (and it's a big if) your finances and family situation etc can take it and you reckon you'll be able to find other work without too much of a gap, don't stay in a job that's making you feel like this. It's not worth it in the long run. Mental and physical health are far more important.
Incidentally, I'm awake because I'm in the US, but will be off to bed soonish because I want to get up at 5.30am tomorrow to watch English county cricket online. Life and soul of the party, me.