Do i have a legit child custody of proving the mom unfit?

Not sure just what state you live in as each are different. I hope you kept the text messages as when you go to court you need prove, not here say. You may want to take a dna since she stated you wasn't the father. Talking to a lawyer is an excellent thing to do, I think things look good for you getting the boy if he is yours. Good-Luck!!