First of all I'll just say that what she did was rape, she deceived you in order to sleep with you. If it was the other way around, if a guy pretended to put on a condom so that the woman would let him sleep with her, then he'd be a rapist. So you could press charges against her for that.
As for the child support, unfortunately I've heard cases where a woman would actually outright drug and date rape a guy to get pregnant, and the guy still had to pay child support. It's absolutely barbaric and shouldn't be the case, but it's happened. But maybe they were exceptions, I'd consult a lawyer if I were you. And if he tells you that you would definitely still have to pay child support, then maybe you could tell her that you'll press charges for rape if she tries to make you pay child support.