My heart just hurts for you and your kids.
My X does not pull this, but I did put in our parenting plan we are both required to get our children to sports, including practices, social events, doctors visits, and counselors. Thankfully he does all of that.
I can only say that if he sees you not react to him much, hopefully he won't use your children as pawns in the future. I agree, what an A$$!
Hugs my friend, tight hugs.