Amy, PLEASE stop hurting your head over who is "technically" or "morally" entitled to more money. The moralities can be debated endlessly. The reason there are LAWS and RULES that govern these things is that for the most part, they are fair. Occasionally someone will get a windfall or someone will pay something they wouldn't otherwise have to pay. The overall system is intended to be fair to all parties.
In this situation, when you are dealing with someone who will mess with your head, FORGET ABOUT the technicalities and moralities. Follow the order, and the law that governs its interpretation and let go of the rest.
I'm not suggesting you should factor this into who owes whom what at this point, but consider all the pain you suffered over the years, the expenses YOU had to shell out as a result of living with this violent abuser. You aren't finagling to get one over on him, but if the way the law works you get a little bit more and he gets a little bit less, so what? Think of it as the universe's way of evening things out a bit.
ALL of your interactions with him from the time of your divorce should be governed strictly by the terms of the order and by the law. Let go of the rest--please. You are burdening yourself without good reason.