Anleja: The relevant statute section is MCLA 722.711 and I have donwloaded a copy if you want. Basically, you will need to get a court determination that the child is "born out of wedlock," meaning the child is not biologically yours. You should really look into getting some legal help as quickly as possible, as it appears that if you are married when the child is born, there is a presumption of legitimacy and your name goes on the birth certificate. You can still fight it at this point, but I think it would be much easier to initiate the divorce now and see if you can be divorced by the time the child is born. If mom tries to say you are the father and liable for child support, you can then get a paternity (DNA) test. Here is a link to the Michigan Court website, which has some additional information. Hope this helps:
http://www.courts.mi.gov/