I'm the problem

I could have been with her a few years ago but I've changed, and not for the better I had a chance to ask her out but I blew it I am quite fond of her but I can't shake the thought that if she ever did at one point feel the same way about me, that's it's gone. She's sweet and innocent, I fear if she gives me a chance that I'll ruin it and hurt her I know the type of person I've become and I perceive I'm not right for her I would cherish our time together if it happened but this premonition kills me.