i fail to see WHY you need to tell him that you filed YOUR taxes and you claimed YOUR children. one discussion about that with him is ENOUGH. you don't OWE him any follow up and ANY conversation you have with the man brings more grief.
so zip it!! don't poke the bear. just leave it be. and i would not mention to HIM again about his being in arrears. he KNOWS that and again, it's just more gasoline on the fire. you can pursue back child support thru Support Enforcement (well that's what it is called here in Washington).
DO NOT ENGAGE with the crazy man!!!