Aw (((Beth))). It is so hard on us when we hurt our kids. Although we don't mean to it happens. You know your son better than anyone else and know deep in your heart how to rectify the situation. I will keep you in my prayers and pray for a peaceful resolution.
I hope they have an extra gown at the school. I can relate, and I'm sure others can, to being so frazzled that we make these kinds of mistakes.
Hang in there! We are all here for you.
BTW- I think I left a blanket and pillow under that rock the last time I was there. Feel free to use them. It's comfy there for a short while but you can't stay there as someone else will need to get under there and there is only room for 1.