The company that my husband worked for said I signed away my rights withe a notarized paper I signed, The woman did not tell me she was a notary.

my husband died this june, He had a woman come to our home years ago and have sign some paper she told me it was something else. I sign it she left come to find out she was a notary and she did not tell me that she did not sign or notarized anything in front of me or ask me any questions, And now I find that the company that my husband worked for says I signed away my rights. What can I do about this I want to get what is rightfully mind. He had a child out side the marriage and we have 3 chhildren in the marriage and left everything to the minor child out of the marriage. What can do to fight this faud