I suggest responding over phone call or in person. E-mails (or texts) will be torn apart and parsed and misinterpreted. Any whiff of defensiveness will be counter-attacked.
Or start with #3 (the short e-mail) and suggest discussing more over the phone/in-person.
What is your parenting schedule BTW?
I've been through a lot of accusations like this during my separation. Neffer had perfect advice. Address what needs to be addressed, otherwise, validate. The distinction can be hard to see in the moment. It will be really easy for her to put you on the defensive... be on guard so that you don't become defensive automatically, it doesn't work.
From the above I gathered you may have a convo like this:
Her: "You don't let me talk to D4 when you have her and she says she misses me!"
You: "This is a delay tactic at bedtime. D4 doesn't talk about missing you otherwise."
Notice there is no validation there and your STBXW would be further inflamed.
The separation anxiety here is your W's separation anxiety, not D4's. It may take awhile to settle down. It may never settle down. If you can empathize with your W's anxiety, that this must be a difficult process for her, while also standing up for yourself, you have struck the right balance.
