Maybe I'm not as strong as I thought

Just yesterday I felt so weak it was almost hard to remember how strong I can be. I was taking the bus to class in the morning and there was a girl on there. She was a college student and I have probably never met anyone who made me feel as bad as she did. She stared at my hand with her mouth literally open. And I'm positive that she was staring at my hand because she followed it with her eyes whenever I moved it. I have just never felt so uncomfortable, nor has a complete stranger ever been so close to getting me to cry. It ruined my whole day. Even hours later I was sitting in my car and I started to tear up about it. Why did I let this stupid girl get to me? I had thought that I was so much stronger than that, but I let her rip my pride to shreds. The day turned out okay in the end because I got to flirt and was called cute by a very adorable boy in the opera, but I still can't believe I let her do that to me. When did I stop being the tough cookie I used to be?