It's not your fault obviously.

He shouldn't have told your daughter he was leaving you
He shouldn't have cheated on you
He shouldn't have checked out without trying to work on the marriage
He shouldn't treat your daughters disrespectfully
He shouldn't treat you disrespectfully

My advice is not to dignify that rant with a response -- rise above.

If you must respond, say something like "I will not correspond with you if you are going to be disrespectful and lob accusations. I want our marriage to succeed, but I respect that you are not interested in that right now. If you want to have a calm and rational discussion about our daughters I will do so. If you are disrespectful, I will end the conversation. I'm sorry you are upset, it's not fair to take it out on me and I will not accept that."

Accuray


Married 18, Together 20, Now Divorced
M: 48, W: 50, D: 18, S: 16, D: 12
Bomb Dropped (EA, D): 7/13/11
Start Reconcile: 8/15/11
Bomb Dropped (EA, D): 5/1/2014 (Divorced)
In a New Relationship: 3/2015