I'm sorry it didn't go so well. I admire you, though, for telling her. I don't think I could have told anyone when I was 19. Actually, I didn't open up to anyone until I was 25, so you are at least more honest with yourself for telling her.
I think you need to ask yourself how important is this fetish to you. If you are like me, and many others, diapers are a big part of who we are and we would be unhappy if we could not be honest with at least one person in our lives. It is so important to me that I can wear my diapers around my girlfriend. If I couldn't, I wouldn't have much time to wear them and I would probably distance myself from her.
So, maybe it was a necessity that you told her, whether the outcome was good or bad. I hope things go well with you two but even if they don't it seems the majority of the members here have found someone who accepts this fetish. Things will work out eventually for you.