Her mother said the attack eventually drove Cassidy to commit suicide.
The family enrolled Cassidy at two new schools, but PTSD and panic attacks stemming from the attack kept her from attending:
"I helplessly watched my precious child wither away before my eyes, mentally & physically, until she rarely got out of bed, until she could no longer take the pain and torment you caused her," her mother wrote in a letter to the bullies on Facebook. "What you did to her was a direct cause of her suicide on 12th December 2015."In a statement to 9 News, the school called Cassidy's death "an absolute tragedy," but did not comment on disciplinary actions taken against the alleged bullies.
In a letter written three months before her suicide, Cassidy tried to tell her fellow students about her experience.
"My aim is to warn other people (students mostly but also parents) about what happened because I'm worried if they could do it to me they could do it to other kids like me, or at least try to," she wrote in a letter provided to 9 News by her mother.
The letter detailed how students harassed her online by calling her a "slut." She said the online torment followed her even after her family moved. Later, she stated plainly, "My name is Cassidy Trevan, and I was raped."
"If anyone ever tries this on you, trust me, it's worth fighting!" she concluded. "Be careful. Be warned. Be safe."
Anyone considering suicide can call the National Suicide Prevention Hotline at 1-800-273-8255.