You don’t deserve her, you deserve someone else who is better suited to you.
Why is telling her that her decision hurt you, not being nice? If you tell her that without anger, and making it clear that you can accept it and move on, what is not nice about it? Do you think that your feeling hurt is in itself, not nice? As long as you are not trying to hurt her there is nothing wrong with letting her know how you feel.
Sometimes this “I am too nice to act in a certain way,” is a way to avoid dealing with an issue thoroughly, and it just gives a person something else to stress about later: “Oh, maybe if I had said how I really felt then, I would feel better now.” So say it (nicely) now and don’t have regrets later. (Of course, you might later regret saying it, the way I might regret writing this and stress out later saying Oh, maybe MiddlePath feels bad and I should not have said this. But I don’t mean to hurt you, this has been my experience.)