I am 100% ashamed to say that I once bullied a girl for a while.
I was heavily bullied myself throughout my school days, and she was a weaker character than me, and it just made me feel so good that for once I was the one in control. As though I was actually able to make decisions, and make other people laugh rather than being the one laughed at.
We're now quite good friends because I apologised, but I do feel guilty for what I put her through. I wonder if the people who were horrible to me feel the same..