Married for 10yrs, separated for 8yrs because I found out that my wife had a kid w/ another man but I signed the birth certificate, now I want to get divorced but the problem is I am in the military and I don't want to pay child support for a child that is not mine (I do not have a relationship with the child or my wife). My wife doesn't want the man she had an affair with to be the father, she wants me to be it because I'm in the military (for benefits) but I don't want to... **note** I married in puerto rico. What can I do?

You might have to start with looking at the state the divorce is going to be filed in. In some states if a child is born during a marriage then the husband is the " presumptive " father regardless of who the bio dad is. You need to find that out first. You will really need a ,lawyer to walk you through all this because of the nature of your marriage. Have you been doing things like married only separate ? ( joint accounts.. helping with the bills etc ? ) Those things will come into play also. You both can maintain separate living quarters and still have a marriage ( in the eyes of the law ). So first things first and go lawyer shopping for a lawyer that can handle your case and do it well. Then you will find out where you stand and that should give you a starting point.
Good Luck

You will have to go prove you are not the father by DNA tests, in most states you can not be held responsible as the father if you prove you are not.