As a previous poster mentioned, I wager that a lot of us can identify with a lot of your feelings and pressures (although I doubt many of us would be able to commit it so eloquently to text) so don't think you're going through this alone.
I've not much more to add to what others have said (particularly Kim), but one other thing that struck me is that you're finally at a self-imposed crossroads. You don't appear to be under any time pressure to act quickly.
Maybe you should try the job out. I mean, if you're willing to turn it down (and face any family consequences as a result), then there's not much difference in trying the job for three months and then quitting. That's probably what I would do.
For me, my work environment has a huge bearing on my happiness and my home life. You might suprise yourself if you take that job and all of a sudden enjoy it. You won't know until you try.
Anyway, good luck and please come back and tell us how you get on.