Who said it was 10 years later? The time to dispute it is when it is noticed. Again Your appeal to emotion fails... You're like an NPC in a game... Same repetitive patterns incapable of independent though or decision making. It would be kind of sad if it weren't so amusing...
Wow, guy, you repeat a meme you heard somewhere else and think you had an original thought.
Guy sounds like a major league creep to me. Then again, he's a friend of yours, so that should probably go without saying.
the thing is, whatever was wrong in their relationship, the kid didn't deceive him. The kid didn't lie when he called him "Daddy". The law is pretty clear... if you put your name on the birth certificate and act as that kid's father, you're his father.