The slip of the mouth

On last wednesday, and and my best mate went to do athletics for my school and on our way back we got talking to the other people in the bus and they started talking about one of my friends ex-boyfriend and my best friend turn around and tells them what she had done with him, of corse as you can imagine, gossip time and my best friend kept talking on, the next day in english i was sitting next to my friend as usial and one of the girls from the bus was behind us and for the next two lessons she kept asking her if it was true, on the friday my best friend finally got convinced to tell her that it was her to told them about it, and my mate stormed off, now i know that it was right for her to want to do that but i just want to know if you think this was right of my best friend and if you have had anything like this befor.