I brought up the fact that she now has to get my name off the birth certificate.

That is not a fact, sir. She has to do no such thing. If you are named on the birth certificate as the father, you need to take responsibility for getting your name off of it. Do not leave that up to her.

There will be a limited time period in which you can legally challenge paternity, so you should ensure that you do this as soon as possible. Call around, find a family attorney in your area. It's basically going to be some paperwork, a minimal job. But time is of the essence.

She was already willing to cheat and lie to obtain your wrongful support. You have to assume she will continue to. Finish off this mess of a chapter of your life up by thoroughly covering your ass on the paperwork end.