Based on what you described, and I hate to say it, it sounds like you already lost. Generally, you cannot raise the same claim that you already attempted in the foreclosure defense (i.e. you only get one bit at the apple, your only next step is to appeal the judges decision).
However, you should discuss the issue with a FL foreclosure attorney to make sure you have covered all your options.
If when you appealed, the mandate was a PCA (per curiam affirmed) without opinion, the battle has been lost. Additionally, as of July 1st, 2013, if a 3rd party purchaser has gained title to property, any lawsuit you might be able to bring will be for money damages ONLY, not for recovery of the property. I have seen others attempt the defense you outline above and fail. Ultimately, foreclosure court is a court of equity, and in the end, the money was lent to you to purchase the property and you did not pay. Please do not take this to mean that there are no defenses to a foreclosure, because that is the farthest from the truth and I defend many foreclosures on a daily basis. However, you need to seek loss mitigation, such as modification of the loan, during the process in order to save the house. It is a common misconception that one is entitled to a free house due to some minor technical deficiency or technicality. Borrowers have gotten the windfall of a free house on very few occasions and generally for extremely egregious violations of law or process by the bank. In the end, the old saying "nothing in life is free" proves to be true."