I would focus on being a parent first. Document all your parenting time. Document all the exceptions.

If the event is that important to you. Let her know you have an event. give her a choice:

H:"W, I will be going to exent xyz this Sat night. Do I need to find a sitter or will you be home to watch the kids?

"What is best for my kids is best for me"
Amor Fati
Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712