The first question I have for you is this: Is he in fact the biological father of your son? If not, then you have nothing to worry about. If he is, he certainly could take you to court, ask the judge to establish paternity (make an official declaration based on dad's admission of paternity) and set custody/visitation/parenting time. I don't see how he could possibly get sole physical custody, though, particularly since you have obviously been by far the primary caretaker since the child's birth. The most likely scenario is as close to a 50-50 split as reasonably possible. If he is the father, I would not deny him time with the child; however, I would require him to initiate any and all requests to see Junior and be consistent and reliable in following through on scheduled visitation. If he doesn't, you can always take him to Court to get an order regarding custody and visitation. If you are not 100% sure who the bio dad is, you can ask the court to order a DNA test so that you can be sure it is or isn't this man. Best of luck to you!