How I learned that she doesn't matter

There is this girl that I go to school with and she greatly dislikes me, if not hates me. How do I know this? She is openly mean to me. I try my very best to be kind to her and not let her get to me, but it is really difficult when she is so hurtful. Yesterday I cracked. I realized that letting her be controlling and mean to me was not what someone like me, a leader, should allow to happen. After her telling me what to do, I blatantly said "YOU AREN'T GOING TO BOSS ME AROUND. LEAVE ME ALONE." I didn't think that she would, but it worked. I know that there was another way to deal with this, but I really needed to stand up for myself and now I feel so much better. Hours after this happened I talked about how I stood up for my self to one of my friends and she told me that I was right, this girl did hate me. At first this made me a little mad, but then I realized something...
Dr. Seuss ones said "Be who you are and say what you feel because those who mind don't matter and those that matter don't mind." After thinking about what this meant I realized that this girl didn't like who I was. And obviously there is no way that I can change that. So therefore, she doesn't matter to me. Seeing as I am leaving for college in 3 months and I will never have to see this girl again, I seriously don't give a shit what she thinks of me.
I feel like this is an epic break through for me. After attending a leadership conference last year I didn't think I was a leader. This tells me that I totally am. It shows that I can speak up for myself and then realize that I am who I am, and I will always be that person and nothing anyone can say or do will change that.