If that is your son, you owe it to him tot get to know him and let him know his father. Maybe it appears that she's done okay for herself, but I'm sure she would be interested in the very explanation you just shared here, if nothing else. I say contact her...see what happens. Maybe she wants nothing to do with you, maybe it's not your son....but you won't know until you step up and say hello.
I agree. And another benefit is that son would want to know health history and genetic heritage too, if you are the father. So put yourself in that boy's shoes.
Man up dip shit. You were man enough to stick it to her, now open your wallet and write her a check for the 18-years of child support you didn't provide. After you do that ask her if it would be ok to be introduced to your son.
Notice the order I wrote those in - write the check first, then ask to meet the kid.