re-my grand daughter

Dear Jeremy,
I would like to get help for myself, to be able to deal with my grand daughter who is 13 years old.She is extremely difficult to talk to as she gets angry very quickly and flies off the handle. I believe that my daughter had a choice in life but my grand daughter never had that.
I am blamed everytime the topic comes up because when my daughter was 15, she became pregnant and wanted an abortion. I did state that if she did that I will not have anything to with her as I am Catholic and does not believe in taking a life, all be it an unborn foetus.
Since then, my gaughter has had 8 partners living with her and her daughter. My grand daughter has been hurt severely everytime her partner leaves and I have seen her supporting my daughter even at the tender age of five as my daughter broke down in tears. This is not what should be happening.
I believe that I can get through to my grand daughter as she comes to my home everyday after school as my daughter has to work late some days. Unfortunately, She is now wanting to be with her friends after school and I do not know where she is after school. We got into an arguement the other day and it became violent. I have banned her from coming back to my home. I know it is the wrong thing to do as my daughter now has to rely on friends to take her in after school.
She said that she is being bullied but I believe that because she thinks as an adult, as she never had time to be a child because of my daughter's lifestyle, the other children at school thinks that she is rude and she sometimes comes accross aggressive. A few days ago, a girl threw a chocolate moose at her and messed up her hair, uniform etc. and she came to my home to get cleaned up. Unfortunately I did not let her in but my husband went out and cleaned her up and sent her home. I know that I should have reacted differently but I was still angry about her behaviour towards us.
I wish that someone will be able to help all of us as a family so a very intelligent 13 year old will be able to do well at school, be able to integrate with her peers and forget the past and move forward. My daughter just cannot move forward. She needs help also and I need help because I cannot cope at 58.
Please help.
Grace