I signed a agreement to relinquish my rights to an unborn child and the mother kept child. What are my rights?

I resided in Oklahoma a few years ago, now living in Georgia. I had an intimate relationship with a woman while living in Oklahoma. She became pregnant and we both were adamant about terminating the pregnancy because she was already in a relationship with another man and didn’t know who the father was. I was also moving out of state. We mutually agreed to terminate the pregnancy. I wrote up a document showing I paid for the termination of her pregnancy as well as uishing my rights to both her and the unborn child. We both stood before a licensed Notary in the Sttate of Oklahoma to make this a legal document. 1 ½ years later I received a request from the State of OKlahoma (third party) requesting I appear for a paternity hearing. I have no desire to go forward with this case as she went against our agreement with out my knowledge and had this child without having even contacting me at least to let me know of her decision. I declined to appear sending a copy of the Notarized relinquishment of rights letter back to the OCSS in OKlahoma. I need to know what rights are. Is my notarized letter a legal document? What are my next steps and do I need to retain a lawyer in OKlahoma? I do not want take any paternity testing or have any relationship with the mother or this child.