I only really experienced having a school bully at the beginning of elementary school. From about ages 6-8, this kid a couple of years ahead of my age group got most of his fun out of beating up kids in my age group during recess and/or stealing/breaking whatever toy you were playing with.
In classic bully fashion, his favourite target was this small boy who was about half the size of the rest of us in our grade.
Then one day he disappeared abruptly from our school. I suppose we all figured and hoped that he'd been expelled from our school, or that his family had just moved away.
A couple of months after our bully disappeared, our teacher sat us all down on the carpet at the front of the class and revealed to us in a gentle tone that he had recently died in hospital. I can't remember the exact details, but it was some kind of kidney ailment. She said something along the lines of "I know a horrible thing like this can be difficult to process, so if anyone wants to talk through it or share any memories, feel free."
That kicked off what seemed like an eternity of awkward silence and fidgeting from the whole class, with none of us saying a word.
The silence was finally broken by the little kid who'd been his favourite target, when he stood up and shouted at the teacher "He was a jerk to me and everybody else, and I'M GLAD HE'S DEAD!!", then he turned on his heel and ran out of the classroom.
Nobody else had anything to say; we mostly responded with shrugs & nods to each other or just looking at the floor. I imagine a lot of us were going through the same thoughts. At that age, you have the vague understanding about death being bad, but at the same time our day-to-day lives were all going to be measurably better now that our school bully was never going to return.
So, that marked the end of our teacher's impromptu group therapy session. And in the long run, none of us really talked to each other about our dead bully again after that day.