While my situation isn't quite so similar, I have recently had to say goodbye to a friend, and it's been more than difficult for me to do so. I don't know if you need to give her space and time to sort out what she might perceive as a betrayal (it may not be, but from what you've described, that may be what she sees it as).

Perhaps you can give her a (temporary) final means of contact. Write her a letter. Be honest. Tell her that you didn't want your feelings to override what was a wonderful friendship. Thank her for her friendship and what she did for you over the course of your relationship. Apologize for not being upfront about your feelings. But don't beg and plead...simply tell her that you understand her need for the space to consider anything you may have written, and when she is ready, you'd like to talk about what happened.

I desperately want my friend back in my life, but sometimes we have to do what we don't feel is the right choice for us, and just say goodbye. I hope that she is able to come to terms with what has happened and will return to your life. If that's the case, promise her and yourself that you will be open and honest with her.