What should I do right now?

[rms_98]

I've been avoiding a girl, whom I shall call Susan Yip. She was previously very mean towards me and I let her go, so as to prevent myself from being more hurt. To sum up what she did to me, here is a summary -
she gossiped about me to her 2 other friends. On twitter, she posted mean comments about me. She even called me names. But she also asked me why I gossiped about her when I only asked others why she was upset with me.

What happened today that I regretted doing -
Today, I saw her at a class BBQ. We were pretty much ignoring or avoiding each other. I think other people realised that too. Then she talked about me to other people during the BBQ. My friend, whom I shall call Yasmin, heard what Susan said about me being petty and other stuff. Yasmin told me about it. It made me and Susan even more distanced. Not many people know that I don't like Susan, but some people know about it already. Then, suddenly, Yasmin asked if I wanted to take a walk along the beach with her, but Susan was already there with her friends. So I told Yasmin this, "Fine. But I'll avoid her." Then Yasmin asked, "who?" I replied, loud enough for a few other people to hear, I guess, "SY!" (I said aloud her initials) And now I'm afraid that others may have heard it and thought badly about me.

Susan is a very well-liked person in my school. So I'm afraid that if she overheard what I said and others too, I am fearful that everyone would just gang up against me and hate me. I really don't want that to happen. Please help me! What should I do?