Over sixteen years ago I married a woman in Veracruz, Mexico. I left her because she was unfaithful and haven't seen her since and don't know her whereabouts. Am I free to marry the woman I now love and mother to my three children whom I live with for 10 years in the city of Altamonte Springs, Florida?

No. Remarrying without divorcing your previous spouse is both bigamy and adultery.

You must contact an Attorney in Mexico and make attempts to contact your first wife and divorce her. She CAN be served by publication following Court Order.

She could also make the same claim against you (if she so chooses) - you have 3 children with another woman. That's adultery.