Passive aggressive on your mad daughter's part, and then in return on your part. I say that with some amusement because I have a mother who could start a PA academy so I know it when I it. It's become a bit of a joke between my sisters and me as we try not to go the same way ourselves.
You were right to delete your response because everyone was trying to suck you in for whatever motive.
I wonder if the EX's GF felt a little frisson of terror at being described as your D's parent?