Okay, my best friend had a huge crush on this guy; she texted me everyday on how much she liked him. He's new to our school and seems nice as we both are in the same Science class. One day, he comes up to me and tells me that he really likes me and wants me to be his girlfriend. Politely, I deny his offer and tell him that my best friend loves him and that I can't betray her (I've been best friends with my best friend since Kindergarten).

He suddenly kissed me and the Math Class came out of the room we were standing in front of, and since my best friend takes Math, she saw me and her crush kissing. I keep texting and telling her that it wasn't true, but she keeps blanking me. Her birthday came up and I wrote her a card, but when I gave it to her, she trampled and spat on it. What can I do to tell her that it wasn't true?