Father Paying For A Child

My sons father makes 1,039.00/month and he hasnt wanted to have anything to do with him i spend almost all my social security benefits on my son each month but his father would rather spend his benefits on his adopted sisters drug habit and alcohol habit i think his child should come first before anyone else does he kicked us out when our son was seven months old and hasnt once tried to come see him but i will not allow him to take my son from my alcohol and street drug free house to go to his fathers apartment where they actually have drug dealers in and out of that place i love and care for my son since birth while i bought his father things and nothing in return plz help lol