Quoting WV momma:" I would want to kick him out. It is Christmas, but at this rate, he won't be there regardless."
This! I also wouldn't take him with on the vacation, he'd probably just make that miserable for you and the kids as well. It seems like he just doesn't want to deal with having a sick child to me, he only wants to be around if the child is healthy and isn't in need of any surgeries. At least that is what I got from your explanation. If that is the case, the kids and you are better off without him.