Sounds like she's testing and wanting control back. Wanting to make sure you are still there.
I'd keep it short. Maybe something like:
"Sorry, I've been busy. If there's an emergency regarding the kids, I'd want you to call/text me. I'll make myself available when it concerns them."
I agree. If she had an actual emergency, she would've let me know.
I dig your text edits. However, I don't want to apologize for being busy. I have considered not giving her any explanation there too.
Here's what I got now: "Hi. I've been super busy. If there is an emergency with the kids, please call or text me. I'll make myself available when it concerns them."
Me:35 W:30 D:4 S:1 Bomb: 01/08/15, discovered EA & PA In House Separation: 01/14/15 W moves out: 04/05/15 I tell OM's W about A: 04/15/15 W serves D papers: 06/19/15 Mediation: 09/16/15 D final: 12/01/15