Need some advice on leaving.

Been with my fiancé for going on 7 years, and I’ve realized he’s just stringing me along and I don’t deserve it. I now want out for sure. I love him, and he is a good man, and I want to marry HIM..But, what if there is a man that I can fall even more in love with, that wants what I want, and I don’t have to question what he wants? Gosh. I am literally scared out of my crazy mind. Any tips or advice on having this dreaded I’m leaving conversation? Thank you so much.