You are valid in your feelings. Feelings are never invalid. But yours have good reason as well. Have you tried calling rather than texting or emailing, or just dropping by n telling her you were disappointed she did not come?

Those things are harder for her to just ignore and even if she doesn't give you a reason, at least you will have a chance to get your feelings out and then you can move on knowing you did what you could, and have a true sense of closure with it one way or the other.