The problem here, as I see it, is that OP has to be mummy who says “actually, I don’t think it’s a good idea to go”, rather than her DH saying “you know what, it was madness to book that ticket, what was I thinking, it’s hideous here this week! I’ll call and cancel the ticket, and tell best friend”... she has been put in the invidious position of being the grown-up.
Anything where you feel as if you’re having to give permission to the other person sucks, and the idea that she has to be a certain level of feeling crap to keep him home is really depressing.
I have a LOT of this in my marriage, and it does not go well.
“I can stay home if you want me to”... well not now I don’t, off you fuck!
Slight transference there, possibly.
Are you both going to spend the last month of the pregnancy watching, waiting, on tenterhooks? At what stage will you feel you have permission to make a fuss. Also agree about farming out toddler, even for one night.
So that’s a no from me then.