help me start over

Please help me fight for my son. I'm the non biological mother. The bio mom and my now ex partner left me. She cheated. And she is now trying to use our son as a pawn. We live in Georgia and they are trying to take him away from me permanently. I don't want to take our son AWAY from her. I refuse to do what she is trying to do to me. I just want to be his parent. I want to be allowed the commitment that we went into when we conceived of our son together. Please. I beg of you - help me fight this. The journey is long and lonely and so expensive. I've been a stay at home mom and partner and I have nothing. Thank you all