Huge fight over nothing!!?

So, one of my (x?)best friends and I were gunna go to a Brooks and Dunn concert this weekend, but I was unable to go at the last minute, the day I told her I couldn't go I also defended my other sooper close friend at lunch, and my (x?) best friend got really mad and stormed off. I knew she was really mad at me when she mad me move out of her locker (which we had been sharing since Christmas) and she wouldn't talk to me. Our other friend got the extra ticket, but my (x?) best friend still won't talk to me!! What should I do?