Am I wrong for refusing to sign the birth certificate of my ex wife's baby until we have a DNA test?

Here is the story. My ex wife, is my ex, because i caught her cheating repeatedly with both my best friend and her boss, I have video footage of it, recorded phone calls, emails, text messages, the works. Before i left her, she became pregnant. I dont know if its mine or someone else's. Obviously if it is mine i will sign the certificate and file for full custody, sorry a cheater is not a good parent to a child. they set a bad example. she's pissed at me that i want the test. That i refuse to sign unless the test says im the father.

Am i wrong here?

Updates
7 mo
the DNA test came back negative, that i am 0% the father. In my state, if the mother knows who the father is, Which she does, He can be made to sign the Birth certificate, Additionally Any child support i would have given would be refunded. In any case im off the hook. And the divorce is proceeding as it should. Additionally the judge agrees with me. She gets no Child support, and because this is an at fault state, she gets no spousal support.
Am I wrong for refusing to sign the birth certificate of my ex wife's baby until we have a DNA test?
Post Opinion