Legal Question in Family Law in Texas

Conceivably, yes. You should really get a lawyer to do this for you. It will involve going to Court and getting an order that makes a finding of the arrearage amount, followed by a formal release of judgment signed by her. Or you can go to Court and ask for a finding that you do NOT owe any back child support (she would allege direct payments from you). If the Attorney General has ever been involved in your lives, they have to be in on the deal; you can't just pretend that they don't exist.