$325,000 in arrears due to 96' URESA

[grassy]

I moved to TN upon divorce in Colorado 1987. Tennessee court modified the Colorado court orders in 1990 reducing monthly child support. Then again TN modified in 1995 raising amount. All payments were made and when TN case was closed in 2005 the court also recognized $24,000 in overpayments.
(STILL WITH ME??)
In 2005 my ex-wife filed suit for $325,000 in back arrears using 96' USESA law stating "only state of origin can modify court orders". NOTE: oldest child was just about to turn 18 and emancipated.
SETTLEMENT: settled out of court in January 2006 for $165,000, of which I've paid $90,000 over past 3.5 years. I'm sick everyday over the fact I had NO legal position to fight the charges.

QUESTION:
Does anyone have a REAL solution to change or amend this URESA law when someone complied with court orders regardless of state prior to 96' ?? or some type of "statute of limitation". This suit was filed 12 years after the law had changed yet unable to contest on this point.

HELP..