To save a friend....

It's always been put out so black and white for us as kids. If someone tells you they are thinking of hurting themselves, tell a trusted adult and get them help. It's the right thing to do...It's what you have to do...you're obligated to do it. I always thought it would be easy too. When people would ask on sites like yahoo answers if they should tell about there friend wanting to hurt themselves I was always like ...DUH. Of course, you're not helping anyone by keeping something like this to your self. Save their life! Tell!
But then it was me. When I heard her say the words...I didn't believe she could be depressed. She was miss outgoing and miss....i don't know. I was just so shocked. Then she said she hadn't told anyone else and swore me to secrecy. I went to bed that night and hardly slept at all trying to think of what to do. Was it my place? She said she had almost done it, but then changed her mind. She didn't trust anyone else and would be embarressed if anyone else knew. The next day she told a few others but I know no one has told since then. I live over two hundred miles away from her, but I worry everyday. I want to help her but I know she would be so angry at me. I don't think she's really thought about it in a long time. It's been over a year and a half since she told me and I think her life has gotten a lot better. I'm just afraid something will happen and I'll think...If only I had told...
I wish it could be as black and white as they make it out to be but it's not. I know I'm not the only one who's had this experience. Any thoughts would be appriecated.