Criminal Law Questions? Ask a Criminal Lawyer.
So unfortunately in the State of Florida there is a very strict recording law that doesn't exist in most states. You can only record a conversation with your customer if you have his consent. You are in a two party consent state. This means you need the consent of all parties that are being recorded. If you are a party to the conversation then you obviously have your own consent, and then you also need the consent of the other person.
So if you recorded this in secret, without him being aware, you won't be able to use that recording for anything. If you do use it, you could risk having criminal charges brought against you. Sorry to have to let you know this but it's good that you are now aware.
Best of luck and let me know if you have any questions.