Ok, I ended up going really short with the email, sent this:

"Hey, sounds like you are concerned that I'm not allowing D4 to make choices and that I'm choosing to keep her from you (both physically and virtually), is that correct? Just want to make sure that I understand where you are coming from."

As I re-read her email for the 5th time (or more) I realized that there is no way for me to even acknowledge without appearing to agree or disagree with her so decided to go the trying to understand route.

M(35), W(35), D(4)
M-9, T-12 Bomb Drop (D announcement) - May 3, 2019
W moved out Aug 13
House sold Sept 25
Papers signed Nov 15
Divorce finalized Dec 12