Wife divorced me without my knowledge, claims on divorce decree there was no child. What are my rights?

My ex-wife divorced me without my knowledge while I was serving in Iraq back in 2009 and got remarried four days afterward. She forged my signature on a waiver to appear in court and also forged my signature on the divorcee decree itself. She also stated that there was no child born of the marriage or none expected when the truth is we have a son who is about to turn three. At first, I was sending her money for the child support without any court order. About March 2009, once I found out that he wasn't getting the money, I stopped. Since then she has moved out of state and refuses to let me even talk to my son over the phone, claiming if I am not going to pay for him, then I will not have anything to do with. Now she says she is going after me for child-supprt and possibly back child support. I don't have the money at this time to obtain a lawyer, so is there anything that I can do to protect myself?