You've got that dream, right? The dream of millions of people reading you work. Well, if you don't let anyone read it to give you their opinion and help you better yourself as a writer, then how will your dream ever have the chance to come true?
Not everyone is a good critic or review. Beware that many, if not most, of the people who will read your story or poem just don't know how to look at a piece. But, many do, and those are the people that will form writing groups with you or spend hours on online communities. So, just because the fear of rejection lies within you doesn't mean they won't love it.
People usually like to find strengths within a piece to rave about--the same goes for me. Find one good thing and one bad thing, at the very least. That's the beginning of a thorough review.
So, if the chills go down your back this Halloween, just remember that not showing your work is much worse than waiting for feedback. Grow some courage and march on.