A Broken Promise

A seventeen year old teenager male, named Justin, who self harms, he's been abused by his father since he was six years old, the people around him began to bully him and think he was a joke, they would laugh at him with their friends, around the age he was thirteen.
Soon, he came out announcing he was a homosexual [Or gay, for the few people who don't know what it is], soon all his trust has been gone, he became anorexic. He would cut so much, his body covered in cuts and scars.
He meets this boy when he turned seventeen, named Zack.
This boy was nineteen, in Justin's eyes he was perfect.
Zack found out Justin cut, He had Justin promise him not to cut himself or try to end his life.
The bullies got worst, his abusive father also got worst, his sister, the only sibling he had who would actually listen to him and help him with his problems, passed away,
Honestly, will Justin manage to keep his promise?