Your story sounds hinky. First off, why would you sleep with someone who claims to be estranged from his wife and on the way to divorce? Why couldn't you have waited to see the evidence (of the divorce) for yourself? Not a bright move there.
As for deleting the emails, if they are threatening you, why would you want to do that?? THAT IS EVIDENCE!!!!
Look, I do understand that your child has the right to receive support, but there are times when one should wonder what the circumstances were that brought this child into the world (mind you, it is not the child's fault; the children always wind up as the victims).