Inlaws separated me from my children after husband's death what to do

Sir, I am a widow of a soldier husband and a mother of a twin sons,after my husband death in a road accident, I was brutually beaten and separated from my sons by my in-laws, they thrashed and sent me at my mother's home. After then onwards I filed an FIR and also registered a criminal case from the district court as per my lawyer advice but I am not receiving any concrete assurance from my lawyer to get hold of my sons, Now I need to file a child custody case through family Court, but where to file, do I need to file at family district court or Patna high Court directly