so, you were banging a married chick who got pregnant around the same time?
If so, I would leave it alone, as she undoubtably told her then husband that it was his, and in the divorce, he will be paying the support. He most likely has accepted the child as his, you would be messing up three lives if you pursue it.
If for some reason you turned out to be bio-dad, what good would come of knowing this information?
Are you going to offer him a refund?
It is about the child, and his relationship with his father.
Reverse the situation. You are (insert age) and find out that mom cheated on dad, and this guy who you never met is now in the picture. Now divorced parents are
really fighting over you, and 'dad' doesn't want to see you any more, and mom is mad because he quit paying her. Now you are broke, mom is crying, and daddy doesn't love you anymore.
But hey... your wife is curious, so what the hell.