It was a scary thing to have happen Cola. How is your DS?

I am a little surprised the class he was in didn't take him along to assembly with them or was he alone?

On top of all the other dramas you have been having this must just feel like the last straw.

What are your options with changing schools or homeschooling or something else because you do not need to have this stress and be worried about what is happening at school all day. You have had some recent success which is great. Do you think it's enough to keep your DS in place?

I know nothing about your legal avenues. I certainly would address it with the Principal and the IEP team as it isn't acceptable. Beyond that the legal stuff might just be ever more stress, but it's your call.