I am surprised no one has mentioned this one yet.
Koe no Katachi (A silent voice) is an anime movie that explores the concept of a deaf girl being subjected to harsh mental and physical abuse in the form of bullying due to her disability.
The plot revolves around two characters (the deaf girl and the male bully) that each struggle to find a middle ground between them due to the latter failing to understand the predicament of being deaf.
As the story unfolds, the hate of the boy is replaced by genuine guilt that haunts him for years after the girl transfers out of the school never to be seen again.
Until one day he randomly meets her and begins his jorney of redemption for the horrible sins he committed.
This movie is a rollercoaster of emotions that will take you on the feels train no doubt.
I definitely recommend it.
PS.: Can post a clip later if you are still unsure.