Good luck to you as well. I don't really co-parent but yet I sort of do. My boys don't go to their Dad's but my 16 year old will go on the once a week thing for a few hours if he isn't working. My S19 rarely does anything with him but then again he has a busy life.
My ex makes the girls do the every other weekend and while I can't agree with everything I know that he does love them. His time and his relationship with the kids are just that, HIS. I only throw a few cents in here and there and he has asked that if the kids are sick I let him know. He doesn't do much about it just knows. I do know that it bothers him to no end that the 5 of us are a family and he is no longer included in that. What can he expect, he left. Anyway, he married his affair partner and he has been considerate enough to not bring her to our kids functions.
As more time passes and you focus on your life and the kids when they are with you, the pain will lesson and you will amaze yourself with how strong you really are.
kat
Me-53(and learning!) S24, S21, D18, D17 Just keep swimming, Just keep swimming. Dory