Middlepath,
Unfortunately I dont have much time, but I want to respond. I am going off my instinctual impression from reading your post.
I think that by being nice by not showing your feelings is not being nice to yourself. You deserve to show her what you are really feeling. And if she is a genuine person, she would want to see how you genuinely feel. You have a right to feel hurt. 100%. I dont think you should walk away without a fight. Of course not to seem desparate or needy, but with your self worth intact, just communicate how you are feeling and if you can ask her how she came to terms with her decision. It may be foward but it will feel much better afterward. Tell her how you connected. How good of a person she is. Again, do this from your heart. Keep us posted! We are rooting for you here.