why does my friend likes to post negative comments about me on fb whenever i make her mad?

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This girl was suppose to be my best friend but I just don't get why she does that to me. Whenever she gets mad at me she will post about it on her fb status which obviously everyone will see it and either like it or comment it making me look like a bad friend. I confronted her about it when she did it again and she just said "I didn't use your name so don't worry about it"...like really so that gives her the right to be that rude to me and to make it well known to her fb friends that me and her are having problems. We're both in our early 20's too were not teenagers so being a kid isn't her excuse. Is that being a friend? She can be a good friend but once she gets mad she likes to go over the top. What would you guys have done?