Is it normal to feel sympathy for someone who has bullied you?

There was this girl at my school who acted nice at first, but was obnoxious once you got on her bad side. She was my friend the first couple years we had class together but you can tell where it started going south. She was very welcoming and inclusive and she stuck up for me when I was getting bullied. Unfortunately, she became that bully a year later. The first part of senior year, she excluded me from cliques and was constantly gossiping. Because she turned out to be a bully and a hypocrite, I decided to find some new friends and I did. Unfortunately, this girl was also rude to my friends and would get smart with me when I try to stick up for them. In the Spring, things started calming down so I thought that I'd give her one more chance. I learned over the months that as long as I stay out of her business and don't do anything stupid, she'll be nice to me. That is until this week, when she started to pick on my best friend. She hurt him to the point where he burst out in tears in the middle of class. They both got called to the principal's office. When they came back, the girl came in angry and in tears, grabbed all of her stuff, slammed the door, then left. She had been kicked out of school. Not only did I have sympathy for my friend, but I also felt sympathy for the bully. Even though she bullied many other students and deserved to be expelled, I can't help feeling bad for her. Is this normal?