drop this because it's pro bullying
In this manga, the author clearly writes bullying as something so horrible and wrong that the bully continues to punish herself to this day and she is never truly forgiven, not even by herself.
That is exactly my problem, bullies in real life never feel this kind of remorse, on the contrary they continue to live in a natural way and in the worst case they are happy and successful people who trampled on the lives of many just to feel better. The manga makes it look like they are really sensitive people, which they are not. Anyone can feel remorse for their bad actions, that being part of the plot so that we feel sorry for a character who was a bullie is pro-bullying.
Nothing in here implies anything of that sort. Most bullies, especially those you described, know exactly what they're doing. Here we are dealing with a character who genuinely thought she was doing the right thing until she found out otherwise. And any discussion of actual bullying here clearly condemns it.