Telling my friend I'm Atheist.

I have a highly religious friend, who i once told i was an atheist she frankly was outraged. She told everyone i knew, when i had asked her to keep it a secret. I told her that i was a re-born Christan and that i accepted Christianity, this was a lie. Now several months have past, almost a year. All my friends know I'm an atheist and have accepted it. Everyone knows.. except for her. One of my friends said i was fake, and that i should tell her. Should I? and if so how?