a note?
Didn't it occur to you to confront her face to face?
I'm trying to figure out whether it is a gender thing or a personality thing. I would have never gone to the principal. I would have told her up close and personal that I was on to her and expected her to make restitution. If she refused I would have threatened to expose her.
Reversing the gender, if he refused to do the right thing there would probably be fisticuffs.
She deserved worse treatment than you gave her and the reaction of the principal is abominable but not surprising.