Why?

Why do I lack such self-confidence when it comes to my husband? I am so terrified he is going to leave me, all I do is sabotoge myself!! Their are so many better choices than me out there. He could have anyone he wanted...someone thin, brunette, petite...all the things that he is attracted to....all the things I'm not. I dont even know why he married me...he will just leave once he finds someone more appealling!!