Help please!!

Hi all,

Got myself in a right sticky situation (6 days before GCSE's start...nice).

Good friends with a girl (there's always a girl isn't there) and in a maths lesson I moved a chair aside as we were walking between two tables to make space for her and me to get through. She said why did you do that so I responded with "to make sure you could get through"... We have a lot of sarcastic jokes and didn't think this would be any different but she took it to heart (FYI she is very strong and skinny).

She also seems to think I have a crush on her as another of my friends who is jealous of my friendship with her spread a rumour through school... Needless to say he is no longer my friend.

We've only had one proper discussion about it and she's very annoyed and convinced I like her. I don't, I like another girl ( I told her who before this erupted).

All sounds very insignificant but she is refusing to acknowledge. We are both in the same group and as such I can't turn to them for help as they won't pick sides. They have asked us to try and sort it out and I have explained my side of the story to her but she doesn't believe me. Am I in the right/wrong and what do I do?? This is also impacting revision sessions, not great less than a week out from exams. Thanks in advance!!