The mother told me she would abort if I didn't. She did an open adoption and has a relationship with my child that I cant. Is there anyway I can be a part of his life?

When you went to court, and relinquished your rights, they made sure you knew PERFECTLY well what you were relinquishing, right? They asked you SEVERAL times if you were being coerced and that you were relinquishing of your own free will, right?

Why in the WORLD, after lying in court and saying you weren't coerced, would you think you'd be able to overturn it now? Do you have PROOF that you were coerced?

Why can't you have a relationship with the child as well? Open adoptions are open adoptions.

Contact the agency used for the adoption, state that you would like to be a part of your child's life through the open adoption, and negotiate to work with the adoptive parents on opening your side of things.