A Broken Friendship?

There was this girl that I was really close friends with who recently started lying to be about stuff. Just little things at first but then she lied to me about something that was rather important to me. And to top it all of she also started to treat me poorly, telling me we can't hang out anymore and then showing up telling me that she misses me. I called her on the lies and such and she just turned it around and made it so that it was my fault. I know that I need to end the friendship, but she is a little niave and doesn't know that anything is wrong. And if I tell her that this is it I'm afraid that it will hurt her more then she ever hurt me. I sent her an email telling her that I wanted to rekindle the friendship. But I now know that she is no longer the same person that i was friends with. What should i do? I can't stop thinking about her and what i should say the next time that we meet. If i should try to pretend that everything is alright to save her the hurt. or just call it.