sharwine - I hope you have a good lawyer. In TN, if a child is born during a marriage, the husband is the legal father whether he is the biological father or not. My ex is benefitting from this stupid law right now.
Now, if she has lied so much are you sure she's telling the truth about the pastor? It would be very unfortunate for you to "out" something that didn't actually occur.
Make sure you start a file and include stuff like the results of your sperm count, any names she throws out as the possible father. You don't want to rely on memory when the baby is born as to who you need to get court orders for paternity on.