I'm so sad to hear your son is suffering like this. A death threat in my country is taken very seriously. 😦 

If I were in that situation, I would homeschool (this is what we do with our four children). I know that's not always a viable solution but where it's possible, it's a great one. Making friends with a homeschool community can replace the need for the school kids 💜💜💜

Most kids escaping school violence much prefer not remaining in fight or flight which is really not good for their nervous systems anyways. It's awful that this is such a prevalent thing in these times. 

A book that helped me understand what's going on with kids like this was Hold on to your kids by Gabor Mate. It really helped me to understand why kids are likely to bully and behave that way. 

I hope you can find a solution that works well for your children 💜💜💜