It's his dad's 60th.
His whole family is going away to celebrate.
As a family, you can't afford to all go.
You don't want to go.
He desperately wants to go.
You think his family are inconsiderate for booking a holiday because your health is not up to it.
You think he's selfish for not wanting to celebrate his father's milestone birthday.
Honestly, you sound entitled. Others' plans shouldn't have to be based on one person's requirements alone. You clearly can go on holiday as you've just been on one a few months ago. You have family an hour away.
What is the issue? Like actually?
You have plenty of time to make arrangements. You're not working. Go and stay with your family for Christmas. Arrange for someone to come and pick you up. Or ask family to come to you and help you host
It's 7 days. If you're able to think about leaving him - that's way more days to do it alone .
Honestly, I'm reading this as a person who's struggling at the moment and a bit sad and frustrated who hasn't yet accepted their medical condition BUT wants everyone around them to feel that way too, inadvertently.
Another option would be for him to go with the children and you stay at home . But as you say he'd starve and live in a pit without you, that may not be practical
IMO your view is clouded by the already existing animosity , resentment and dislike of your DH and his family.
I hope you get some resolution with endo. It is a horrible, misunderstood debilitating condition. And it makes people cranky, can cause mental health illness and gets little empathy from others. How we manage that is our choice. How we decide to live with that is our choice.