I think its too late for that, I would have sent that earlier but too much nastiness back and forth has transpired. How hard is it for her to just say they should be leaving around XXX? seriously?
It's not that it's hard, she just wanted to lash out. lol
It's CB, plain and simple.
It's never too late to lead and show her you will not be bullied into not seeing the kids tonight.
It's just you need to control your emotions now to do it. Let her burning anger missles bounce off you as you go forward for your kids.