As a teacher, I once somewhat concerned my principal when I showed Darren Aronofsky's "Pi" to my 11th graders, half of whom were Arab.
I only read the first line, but if my teacher tried to make me to watch brokeback mountain, I'd give her a cucumber and "peace out".
If your 12 year old kid suffer from psychological distress after seeing that movie, maybe there is something wrong with your kid. It was still pretty stupid from the teacher to show a R rated movie to 12 year olds.