Backstabbing!

We've all done it at least a few times in our life but seriously once you hit grade 12 I think it's time to stop! I can't believe it though that at 17 years old a girl can just say to someone that after a long time of having a super close friendship with a person, she asks herself everyday why she's even friends with such person. I mean when you hear such things behind someone's back would you tell them, especially if that person was also your best friend, I know I would okay well I did. I don't know if I did the right choice or not but backstabbing is stupid and hurts! What would you have done in my shoes?

My Story:

One day, during lunch, I went to talk to my friend very quickly leaving my other friend alone for a second but when I turned around to talk to this guy that I needed to show something to, my friend I went to talk to, said to this one girl, that asked her why are you even friends with her, that she doesn't even know and she asks herself that everyday. I just walked away to my friend I left alone very quickly because they were talking about her. And I told my friend right away and she was upset to the point that she was so mad. Ever since then the two of them haven't talked to each other and I haven't talked to the girl that said that either because she really hurt my best friend's feelings. I think she did anyways.

But still I don't really know if I did the right thing by telling her or not I just find that backstabbing is stupid and even now the girl that said that keeps on saying mean things about my friend!