This is much more complicated now that you have a child. There is no 'easy and cheap' way to do this without knowing where your ex lives since he is the legal father of your child. You need to consult an attorney face to face. Best of luck.
This information is a general answer and is not specific to any particular case. Carin Manders Constantine, Esq. 727-456-0032/ 727-488-8272 familylawyer411.com/about-carin https://www.facebook.com/pages/The-Law-Offices-of-Carin-M-Constantine/125967577416313 http://www.linkedin.com/pub/carin-constantine/b/861/445
You should contact a local attorney about doing a diligent search for your spouse - and, assuming the spouse can not be located - what the requirements are for alternative service, usually by publication.
Under the rules governing the conduct of attorneys in New York it may be necessary to remind you that this answer could be considered attorney advertising.
Unfortunately, there is no quick and easy dissolution in your situation. Under FL law, paternity for your child is presumed to be your married spouse. A consultation would be necessary to get the appropriate details for your case.
In any event, it is highly unlikely that you would be able to get divorced by year's end in order to get married to your fiance.
Sign up to receive a 10-part series of useful information and legal advice about the divorce process.