Clearly the right answer is to save your marriage - a divorce will cost you way more than you would probably earn!
In all seriousness, if you were only a couple years away from FIRE, I would suggest to stick out the high-paying job (that's what I've chosen to do), but you are still a ways off and you'll want to have a happy life in the meantime. See if you have any negotiating room with the new offer - let them know that you've been offered 50% more and you're seriously considering it, but would rather work for their company, but you know, it's 50%! They'll see that you're caught between a difficult decision and that you're just not out to be greedy. OR see if you can negotiate for some other perk, like an additional week of vacation.