My thought turn to my grandson. My daughter got involved with a man who is my age. She became pregnant at 18 and lived with him for several years. I was talking to a Director of a Child Care Center in my town and mentioned my grandson's father, she said "please tell me it's not ***********". I said "Yes, that's him", she proceeded to tell me that about half of the mothers in her center, which is licensed for 100+ children, say he is the father of at least one of their children. My grandson will have to talk to the mother of any girl he dates and ask them is it possible your daughter is my half sister. Even though the father of your child is in another state he may have other children too.
Another thought: if you ever have to apply for any type of aid, such as a medical card for insurance through a state agency or food stamps, etc...the economy is bad for lots of people and a person can be out of work in a day or two, then they will force you to sign papers for child support.
In my opinion, mine alone, I would have to tell him. I think morally that it is wrong to keep a child from a father. He may want to have arranged, formal, visitation or may not want anything at all but it is his child.