I was raised from a child-4-years-old by my mother and my stepfather (my biological father abandoned us). I never took on the last name of my stepfather, who died when I was 43-years-old. My mom and sibling just received monies from an abestos lawsuit, but I didn't receive any monies because the attorney told my mom I was not his legally adopted child, even though he raised me a child. Is this true?

Yes, it's true - you become a person's child through birth or adoption.

Many people raise other people's children. That does not make them parents.

Are your mother and half sibling planning to share with you?

It is true, you are not his child, your father is still legally the other man. You have no rights to the money.