The only thing "immoral" that Bella has potentially done is fuck the mc while knowing full well that her best friend (Jill) was interested in him. But as they say, all's fair in love and war.
But she definitely didn't fuck "multiple students", just one student multiple times.

And I can't think of any violence she used (other than the Ice Queen in the DnG game, but that wasn't her). And her suspected murder room isn't an actual murder room, so she can't be condemned for that.
So yeah, I don't think she's in the "fucking choir boys" category...