Great job Rain, short, to the point, no blame, no punishing, just about logistic with the kids.
Honey, I know it hurts a lot, and that is why I ended up making mistakes, because it hurts. The sooner you get what works, the better it is for him to notice you won't put up with this kind of behavior from him.
Next time you can text: "H the kids will go to bed early on XMas Eve so they can wake up early to open their gifts. You are welcome to see them open the presents. Please, let me know what time you are thinking to come.
The: "not to worry about cutting his evening short" and "he shouldn't have to eat two dinners" ... they are still the knife you want to put on him.
Yes, he has his plans and it [censored] that you need to know about it. But do not fall for his bait, he wants to push your bottoms and he knows where. Do not react, take your time to answer his texts, read and re read it before you send it.
Maybe you can try to make some plans on your own with the kids. Family, friends? He should knows you are not sitting around waiting for him to be your world, your life. Show him you have a life on your own.
If he sees you nagging, mad and sad, he will be thinking it is all the same with her. If you are out, enjoying a holiday with your kids and friends, happy and busy, he will see that he may lose you and the kids too.
Also, great job on hating him and not letting him know.
You are doing great, get some exercise while the kids are in bed, keep moving...