Is she lying about having cancer?

One of my best friends told me she has breast cancer. She's 15. I moved away from the town she lives in about 7 months ago. In April, I was told she had breast cancer and I cried for nights. I've been calling her and talking to her and supporting her for this whole time. Back in april she said she found out she had it 4 months earlier, which was about 7 months ago. She said shes done surguries and they are sure she has cancer and it is spreading. She said it was spreading so fast that there is no use in taking chemo and she's dying this summer. I believed her all along but ive had a bit of doubt in the back of my mind when my best friend who sees her almost everyday says that her story just doesnt add up, and nothing seems right. She said she thought she was lying even though she really didnt want to believe that the girl was lying about something this big, but at the same time she wished it were a lie because none of us want to lose a friend soon! Well recently, i had been trying to reach her but she wouldnt reply to any means of communication. She reached my friends who told me that she is now cancer free and is feeling much better. She sent me an email sayng the same thing and i told her i was extremely happy for her. I asked her how she found out, like whats the details and she said she doesn't know, that the cancer stopped spreading "i guess". Now people are doubting her story.... thinking that it was a lie all along, and she says that shes glad she has me because im the only one that "understands". What do i do? Is this just a big LIE?