Well, you may want to consult with an attorney, because in essence, he is in contempt of court for not paying the support, even though she said she didn't want it. If that was the case, she should have had the order for support terminated. Since it was not terminated, he has acrued arrears for 15 years of not paying. HOWEVER, I seem to have read something about a statute of limitations on how long it can be collected or something, I'm not sure if it's applicable in your case though. You would really need to seek counsel to answer that question. As for jail, no, it's not likely that they would jail him for not paying, since she did not pursue him for the support, and since he is paying now. If I were you, I wouldn't wait around to find out, though. I would contact the court and find out what arrearages had accrued, tell them what happened (they don't care much about he said/she said, but it's worth telling them anyway) and that he will be paying again. It's likely to trigger a court date for him, but even then, they will just set up a payment schedule, so long as he adhears to it, he won't have any trouble.
If you contact the court, and find that the arrears figure is an unbelievable sum, you may want to offer her a lesser lump sum payment to "cancel" the arrears (if you can manage it.) A lot of CP's would rather take the lump sum than get a dribble of money every week. Do EVERYTHING through the court, though. Don't take her word on ANYTHING. If you end up in court over the matter, the judge can also order a lesser amount be accepted for the arrears. Here is some information on your support laws:
http://www.leg.state.fl.us/Statutes/index.cfm?App_mode=Display_Statute&URL=Ch0061/titl0061.htm
You may want to particularly read section 61.14.
Have you considered having your husband tell here that he is insistant upon exercising his visitation rights? That might be a worthwhile venture, considering what happend 15 years ago...
Good Luck!