The next time she asks you for something like that, before she gets into it cut her off.
Example:
W: I need you to take the kids two days earlier because I have a baby shower to go to.
You: Sorry, you agreed that when we corresponded it would only be about the children. As this doesn't pertain to them, you're going to have to hire a sitter.
W: What?! I'm going to get primary custody of the kids.
You: That is a matter for the lawyers to take care of. Please be aware that I have transcripts of all the conversations that show you wanting to leave the children with me all the time, so I would be careful about threatening primary custody. Have a nice trip.
Just like that.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.