You very well may have a claim for defamation. You should immediately contact Craigslist and ask them to remove the posting. You should also send a letter to the person who posted it putting them on notice that you may be filing a defamation claim against them. Under Florida law, you may be able to prove defamation pe se, meaning you do not have to prove damages in order to win your case. All damages are determined by the jury after they have heard all of your specific evidence and the other person's defenses. You should consult with an attorney to go forward.