My question involves child support in the State of: Oklahoma

Well I don't know where to start, I was young, 18 and met a girl and she ended up pregnant, she was involved with a military person I was not aware of and she and him wanted to adopt the child, she moved to new York with him because of military reasons. while at Fort Drum she sent me papers from her attorney's office, and I even spoke to him. I was advised to fill out the areas that had the green arrows and make a copy for myself and notarize it and send it back certified, it was like 20 something pages of stuff. While speaking to the lawyer he made sure I understand what I was doing and I agreed. One thing he made sure I understood is not to go looking for the child, call or bother or even try to check up on. I explained no problem he doesn't even know I am the dad, the other guy was there for everything and been with them the whole time. I agreed and moved on with my life. I moved from IL where I lived at the time to Oklahoma. She had since moved from new York to Hawaii I was advised by my dad as she contacted him one time to get family details because the child became ill. I never knew they talked or was never asked any questions on this. In fact I got notice at my job one day in 2011 asking for information from me from the state of Florida? It was brought to my attention and I quickly made a phone call to see what was going on. when the name came up I flipped and said I signed all the papers for adoption and followed the attorneys orders to never bother them, They state of Florida quickly got back to me and said what do you mean you filed for adoption. I sent them the forms I had and sign and notarized and sent back. I didn't hear from them for 2 years and last year I get served to go take a paternity test. I took the test and two weeks later I got a call for a court date in mid 2012. I show up and of course with an attorney thinking I was the stuff because I signed all that stuff ad the mother openly admitted to never paying the attorney the rest of them money for the adoption, openly stated she never tried to contact me, Never tried to file for support, never asked for help or even bothered to look for me. openly admitted to all this in child support court over the phone that. The child judge still awarded her 26,000.00 in arrears, and 400 a month. This as destroyed my family. I had married and have 4 kids of my own and have a house to pay for, It is rough as my wife is going to school because at the time of this we thought it was ok, I didn't have any expenses or anything like that and no we are barely making it. I have since requested the transcripts for this and filed a case in district court to see if I can over turn the arrears. See in Oklahoma they put this stuff on your credit and it has stopped me from getting loans, caused my card balances to be lowered with out being told making my bill more and my insurance change price. Seriously? How is this right and I have no idea what to do at this point.