My ex had a car that he paid for before we met and later signed it over to me, so the title and insurance are in my name, he is taking me to small claims court for replevin

Has he taken the car bck yet? What defense is he using that it is still his since he signed over the title ?

Is he claiming that you got it 'wrongfully' somehow? Deceit? You didn't hold a gun to his head.
I would guess that he doesn't have a case, because you didn't commit fraud, presumably, but judges in small claims have a lot of leeway to make arbitrary decisions.

If you ditched him right after getting it, convincing him that you needed it for a job, for example, who knows, you might lose. How long were you together, and how long before you broke up did he sign it over to you? How much is it worth (what year and make)?

Replevin is a civil action to recover a piece of personal property that a person refuses to return to you. In a replevin action, the plaintiff, your ex, must prove he has a legal right to the possession of the property, such as ownership of it, and that the defendant, you, has wrongful possession of the property. From what you have said, I don't see that as the case.

Of course, a judge can pretty much do what they want but if that title is in your name and he isn't on it, then that car is pretty much yours.

And do you have a question?