Mishka, I don't know if there is an answer that we can give on this. With an MLCer, they are very self-absorbed and feel that others need to consider their needs instead. During most of their lives, they have felt that they ignored their own needs and now it is their turn.
Your H probably feels that he has a right to change his plans at the last minute. The unfortunate part is that it is difficult to put your foot down without making it worse.
My sitch is where I always have the kids at some time or another, i.e. my W never has my D when she has my sons. So even if my sons are gone (2 - 3 nights per month), I have my D. When she had my D on a trip, it was my sons and me. I have been able to take off for a couple of hours at times but nothing substantial. My W is not even involved with their schooling or extracurricular activities. I will say my W has recently started to pick up our D after an activity at school (although she forgot to pick her up yesterday ) and she is going with us to a scouting event tomorrow night.
So, I am not giving you an answer or maybe I am. Maybe I am saying that you may need to weigh what is most important to you.
Me:56, W:51 D:26,S:24,S:22 Married:18 Bomb 9/27/06 Separated 11/27/06 Divorced 10/6/08 Leaving it up to God