I ao not know. There are no words for this, there is no way the awful pain will ever really go away for mom, dad, sister, etc, The people who were responsible most likely thought of it as just ‘fun’. Casual cruelty is such an easy thing to get into. But this is just beyond tragic and into a universe of meaningless cruelty for its own sake.
As they get older, I would imagine the kids who did the bullying might be a bit scared to sleep at night, knowing that they took the life of a 13 year old who had his entire life ahead of him and had probably done them no wrong of any type. Very sad.