I shouldn't of engaged but I did. I kept it very short. I text back " the amount the court order says to pay."
While you understand you got too "hooked" into this (and you did)... .the real focus is on your response.
However you arrived at that, it's sometime to replicate. Succinct... .factual... .and devoid of details to argue over.
I've going to say you "really wanted to take the bait"... .but didn't. For that you get some serious thumbs up!
Am I correct in an assumption that you have responded more forcefully to your ex in the past... .that this was a "productive bait" for her in the past? I would guess she will keep "going there"
Hang in there bus boy... .I used to be a Shoney's waiter (many moons ago... )

FF