Well, IMO, you need to do some real deep soul searching on this and ask yourself what you hope to accomplish if you pursue this. I don't want to sound mean, but you let it go for 15 years and now that you find out they are close by, your suddenly motivated to do something about it. Have you asked yourself why now and not before? Like cudaguy said, this is an all or nothing deal, you can't be part in. I'll also agree with the_engineers in that if she EVER received any aid from the state whether it was food stamps, day care, or anything, you can become liable for that restitution to the state once you prove paternity. Granted, the state may not ever come after you for it, but it is posssible they will. Aside from the finacial implications, also consider that you may have a child who we know has no memory of you and may potentially not even know you exist. If the step father has had himself put on the birth certificate and the child has been associating themself as his child, imagine how having you suddenly pop into the picture can really turn that kids world upside down, rich, poor, or not.
Having been in a very similar situation once myself, I can tell you it is tough, it can get ugly, it will be expensive, and it is an emotional roller coaster. Once it is all said and done and over with, you may have found some long lost thread of your life that you always knew was missing, or you could open a can of worms that never really goes away and only marginally gets better. Tough call. However I will tell you this for certain, if you pursue it, do it all above board and legal. DO NOT agree to anything, sign anything, or enter in to any type of agreement with your ex, her husband, or anyone else involved in this without legal representation or review. Doing so without representation can only cost you more time, expense, and heartache.
This can be one of the hardest things you ever have to decide. Good luck with which ever way you decide to go.
