Child abandonment and remarriage by father.

I was 6months old when I lost my mother. My mother's side of family accused my father for it and filed a case on him for it. Fearing the safety of me and brother, my grandparents (mother's parents) brought us to their home saying they would raise us as their own kids, which they did. Gave us quality education, made me capable of earning my own bread. My question is why didn't my father try to get his own kids back. We were his biological children, he failed to get us back and gave up on us and went for another marriage in no time. My grandparents are nomore now and all their children have families, I don't want to be a burden to them as it would damage my self respect. I lost my brother too, in the year 2013 and yet there was no sign of my father . I'm currently pursuing my PG in computer science, 24 years old and yet there isn't any sign of my father asking for my existence. I want to accuse him for abandoning his child and not checking upon me during any kind of crisis. Be is emoti