Ex uses intimidation techniques, out and out lies, questioning my integrity.. anything at his disposal to achieve his goals all the while extolling his virtues.
You do that to get what you want.
You have lots of choices. Pay her what she wants as a way of getting her off your back. Hopefully she doesn't come back for more. Quote the divorce settlement papers as a guideline for what's required that was agreed upon by both parties. Lay out your boundaries of what is and isn't fair and equitable.
If you want a fight on your hands, tell her what she should do. If you keep it impersonal and businesslike, the only thing she can argue about are the facts. As far as taking a loss on the ring, ex and I had to liquidate all our stocks and bonds (at a significant loss) to repay part of the legal fees. It is what it is. It's one of the hardships of divorce.