I'm a lurker from the SP board and just wanted to give my two cents, first off I do agree no matter what your H should have a CO in place.
From a BM perspective I understand stand why she's upset your h and his family hasn't seen LO for holidays in 2 years. If I sent my LO to be with her father for Xmas I would hope he would spend it with his family so they could spend time with LO as well.
But if I were you guys I'd keep LO until after dinner, BM shouldn't go back on her word.
I didn't say his family hasn't seen her in two years. MIL and BM are friends, and live 2 minutes from each other. They hang out all the time. MIL cut us off over a year ago, so we're not seeing his family. It's a bit complicated, but it's mainly because we stood up for ourselves. BM is taking SD there sometime in the next few days.
Also, we've never had Christmas because she didn't want to give us Christmas. It didn't fit with her plans.
She has to work tomorrow, which is why we have her without a fight.
ETA: I do understand your pov though