wow -- a jurisdiction problem again.
I think your main problem is that nothing was ever followed through to a court ORDER. It was all a handshake.
Dad lives in TX?
I think I'd file a "Motion to have your CS Case Reviewed and Closed, and to have the child emancipated" in Texas.
Then when Texas says "NOT my problem."
I'd take that order to GA and file the same motion.
HOPEFULLY, even if you had arrears, you've kept detailed documentation of what was paid out over the years to back YOU up.
This stinks....and it will take time to clear things up, that's for sure.