Sorry Clay, your current dynamic sounds stressful. I have similar scenarios at play w/ my stbx but not as severe.
For her to use your daughter as leverage must be very hard to deal with and its unfortunate for all of you.
I don't think we will ever understand their level of anger and resentment. I have come to just accept it and also accept who she is with no judgment. We can't own their emotions.
I find myself putting on a business mask whenever I have to correspond with my stbx. This keeps my emotional guard up and I do what I need to do and then get back to my life.
Its difficult sometimes because I have 3 kids w/ her and we have to communicate almost daily.
Have you had any success with her in trying to set some boundaries?