Legal help

My name is Donna. I am the mother of this beautiful girl. Her great grandpa on her dad's side sexual abused her so I am going for full custody and taking ever precaution to protect my daughter from that side. I have called the police and am working on putting that man where he belongs. She has never wanted to go there and always cries when I tell she has to go. Her grandma on that side makes fun of her calls her fat and they talk shit about me to her. . She will tell me they punish her differently than her brother which always raised questions to me. Please help me help her.