Tell a lie often enough, and it will become truth.
Parents need to get their children out of there now. They need to take a stand. If they don't stand up to this, their children may be damned.
Anal fetish has no place in a school full of young children. Why not teach animal sex, masocistic sex, sex with students in lower grades? It's all the same.
If it's "all the same" to you you need some help and quick.
Give them time.