My heart goes out to you and your son. It must be a lot for both of you to handle, I'm going to keep you guys in my thoughts and prayers.
I don't know what to do as far as the school is involved, but I would make sure your son is out of that woman's classes or doesn't go to the side of school she works in, if he's able to. If not, I might even keep him home until someone contacts you back.
If you can, I would contact the principal of the school, and if that doesn't help, go higher up and contact the superintendent. This women needs to be removed asap, and the people working with her need to be severely reprimanded if they let her walk away from this.
It might even be helpful if you two can somehow talk to the other survivors and their parents to form a bigger group so you can't be ignored, and to support each other in the community.

Can you and your son freely communicate? does he know he can come to you with personal things like this? In the mean time, if you can't get a counsellor for him or are waiting for one to contact you for him to see, I would try to just be around him and offer support when he needs it. I'm glad he has a mom like you to fight for him.
Take care!