i don’t know what to do

my sister was raped by a old friend of hers. she doesn’t want to press charges because she thinks that if she loses the case, she will get bullied at school. i understand and respect that but i’m just so angry that he hurt my baby sister and he’s not getting any jail time or anything. i’m just so mad i want to talk to him and explain how much he hurt her and i want to tell him everything that she has already been through and how he fucked her up even more than she already was bc of everything that she has already gone through in her life. bc she has not had an easy life and he just made it harder for her. he absolutely disgusts me and i want to tell him. i know it would be a bad idea to try to talk to him because he is dangerous. but i just want to make him understand.