We have to grieve, grieve the loss of our expectations for our child. The prom is insignificant compared to his recovery. My son went to prom, played all the h.s. sports, girlfriend was a cheerleader, got his diploma,accepted at college. Then kicked out of Univers. and addict every since. My expectations now are very simple:
stay alive, stop being estranged and get sober. Are kids have their own jounery that is incomprehensible to us, yet it is what it is. It sounds like your son is headed just where he needs to be going on Thurs. so that's a good thing.
I too spent yrs. working with teens. How ironic for us. We have helped so many kids realize their potential and yet our own kids have made deals with the devil.
I am rambling here...as odd as it seems can you be glad and find some satisfaction that your son is headed just in the dir. he needs to go?