I know that you are pro-se and you may want to or need to continue to proceed that way, but I think that you should consider taking the time to at least consult with an attorney on this matter.  from my understanding mediation in Florida is non-binding UNLESS the parties reach an agreement.  You reached an agreement.  So now you have a contract.  And from what you have stated here it appears that you entered in to that contract under DURESS, which is a valid basis - if you can prove it - to try and set it aside.  You need to focus on contract law and not necessarily divorce law, although that is certainly a part of it.  You need to discuss the right to appeal and other procedural issues with the attorney as well.  Good luck.