Tight situation in school?

I am in a very tight situation in school. There is this female prefect, who says that I like another girl in school. So, I posted on her Facebook and did the same to her, saying that she likes another boy from school. However, she gave me a very bad scolding the next day instead, in front of lots of people. Today, she came to scold me again, with another friend. She claims that I am spreading some **** about her, even when I am not. She even threatened to tell the Discipline Master about what I am doing on Facebook. I just posted on my Facebook status that i had a bad day in school yesterday. However, I wonder why she is so sensitive to it and even confronted me. She scolded me so loudly today, and a few teachers walked past(But they did not care), and I was very embared. What should I do? I am so annoyed by her! Today I just deleted her from my Facebook and left a polite message on her wall stating that if she needs anything, message me personally. I feel so trampled on.. I was so frustrated that if it were not for the boys in my cl who tried to cheer me up, I would have gone berserk. What should I do? I think this is very unfair.