My abusive mom is in jail and I'm guardian of my sister. She's having problems at school.

Our lives have been turned upside down in the last 3 months. I'm 20 male. My sister is 15. I'm gonna explain what happened.About 3 months ago my mom and her boyfriend wanted to go on a vacation and wanted to take my sister with them. My sister didn't want to go and insisted to stay and eventually our mom agreed to leave her with me for a week. I was a little surprised that she didn't want to go as she loves traveling but I was happy that I had this time with her.During this time she slowly tried to tell me things. And I learned that our mom has been physically abusive towards her. She hit her regularly, she locked her in her room, she shamed her at every chance and she even spanked her as punishment in front of her boyfriend. This wasn't some random padding on the butt, she was actually hitting her with something while naked. Apart from the physical pain, I can't imagine how humiliated my sister must have felt going through that.We went to the police and told them everything and they arrested my mom and her boyfriend when they were back. They found a lot of drugs on them as well. My mom has been doing drugs and her boyfriend was her dealer too.Now they're away and my sister is living with me and I want to make sure she's alright. She's seeing a psychologist who is a specialist in teenagers with history of being abused and I'm sure she's helping her. The problem now is at school where everyone knows of our mom now and they're giving my sister a difficult time. She told a friend about the physical abuse too and that friend told everybody and kids keep modking her for it. Her friends don't talk to her, they mock her for having a drug user mother and she feels lonely and isolated.Is there something I can do? Is it a good idea to talk to the parents of her friends to try to understand why they don't talk to her? Can I say something to school? I appreciate the help. via /r/Parenting http://ift.tt/2encnH6