My wife has a son by another man. She had an affair approx 2 years ago and the little boy is the result.
His biological father wants nothing to do with him and I am the only father he has ever known.

Do I have any rights whatsoever where this child is concerned?
Do I have to adopt him and if so what if his biological father will not cooperate?
My wife and I have been married for 10 years now and after some rough patches we just want to be a family and raise our son the best way we can.

We currently live in Chicago.