I would consult an attorney. Most offer free consultations. An attorney will want to look at the promissory note. Based on what you have said you may be successful in winning a suit against him, but collecting the money once you have a judgment could prove more difficult.
This answer should not be construed as creating an attorney-client relationship, and is for informational purposes only.
More than likely you would have proof of his debt.
But you're in FL. They have some strange laws down there.
Consult a FL attorney asap. Is boyfriend collectable? Does
he have a job? Property? Bank account? Good luck.
THIS ANSWER IS PURELY FOR ACADEMIC DISCUSSION ONLY AND DOES NOT CONSTITUTE ANY TYPE OF LEGAL ADVICE OR LEGAL REPRESENTATION.