So sorry to hear about your son. I’m a foster parent and I’ve dealt with bullying schools more than I can remember. It can be heartbreaking. Bullying can lead to really serious mental health issues, and a lot of people just don’t take it seriously enough.
This infographic that the fostering agency I use distributed gives a few warning signs that the bullying is developing into something more serious.
Have you considered switching his school? Sometimes, no matter how much the school tries, the damage is done and the only option in a fresh start.
I hope it works out for you both,