(spoilers)
One criticism I have is that the sister's suicide felt kind of abrupt. While it is possible for someone to end their shortly life after a single traumatic event, what seems more likely is there would be other factors at play. If the teacher had some sort of blackmail over her, maybe a photograph or video taken during the assault, then the victim would feel much more trapped and likely to take drastic measures. Another option would be if the sister was shown to struggle with depression prior to the assault, maybe due to the loss of her mother and unfortunate life circumstance, then it would make sense for it to be the final push.