My wife and her ex-husband divorced back in 1997. Her son attended a 2yr technical school in 2006 and 2007. She took a pel loan out for him but never had her ex help sign or pay for the loan. She is still paying for it. Can she legally have her ex help pay for this loan now after all these years?

Not likely. Unless the divorce agreement specified that he should help with secondary education, then he isn't required to.