You need to contact an attorney immediately for legal advice and to have someone start working on your case. It is usually imperative that the defense lawyer have her or his investigator start working on a case like this as soon as possible. Night clubs are full of witnesses but every day that goes by makes it less likely that your investigator will find the right witnesses or that those witnesses, such as patrons, bar tenders or DJ's, will remember.
First offense or otherwise, this is a serious charge that can have dire consequences for the rest of your life. We cannot give legal advice in this forum and you will need to get that advice from a competent and vigorous criminal defense attorney licensed in Florida. I just write to urge you to call someone as soon as possible to get that advice and to get that investigation going.
In addition to Mr. Sanger's good advice above, I would advise you to stop talking and writing about "what you did." From here on out, speak only to your lawyer and his personnel about this case. In Florida, you can be arrested for a charge but not actually charged with it by the Office of the State Attorney. Hire a well experienced criminal defense lawyer as soon as possible and allow him or her (NOT YOU) to offer your side of the case to the State. Good luck.
Aggravated assault is a 3rd degree felony punishable by up to 5 years in jail and a $5000.00 fine.
We are a Lakeland law firm and would be willing to discuss the specific details of your case.