This:
taking this job requires you to make huge fucking sacrifices "for the family", i.e. for your DH to not have to behave like he has one.
That's the point really. Not whether you will all have more ready cash as a family, or whether his job is getting stale and he needs to move one, but that he has just had a baby, and then said "hey, look, I am being offered this fab new job. You'll be ok working and looking after the kids on your own through the week, yeah?"
All of a sudden wife has to fit everything in her life round her husbands schedule, and that's just the start.
There is always this idea (and I never really realised how prevelant this is until MN) that mens jobs are somehow more important than women's, and it's necessary for ther wives to step back so they can be supported through their careers.
The thing is, OP has a goodish job too, by the sounds of it.
I can't imagine what her husband might say if she told him she was off to a new job where she was only home weekends and left him holding the baby on his own all week, in addition to his own, now lesser, job.
And this situation, where we assume that mens jobs mean more, leaves women, years down the line from having the 1st baby, going part time, not progressing up the career ladder, because someone has to be home for the kids, having less and less financial security in the event of a split etc etc ad infinitum.
I'm sure the husband does need a career boost, but frankly, he has chosen to stay put for 18 years? Maybe he should have thought to step up the career earlier?
Now is not the time.