I've always been really shy about my work, and I've never done much self-promotion until recently. By some miracle, a lot of people found my work even without me advertising and I've never really gotten any rude comments on mine--some constructive criticism, but no mean comments--and, in fact, most of the comments I get are very nice! I would just suggest you put yourself out there. Here's how I convinced myself to put myself out there more: I always just force myself to think of the worst and best case scenario.
The best case scenario about self-promotion and putting yourself out there is: A lot of people will look at your work, and you can gain a lot of fans and maybe even some friends for it. You may even get some (hopefully) good constructive criticism!
The worst case scenario is: One jerk might come by and trash your story.
I think it's a good tradeoff, myself. As a suggestion, whenever you ask someone for constructive criticism and they answer, have someone you love (a family member or a friend) read the constructive criticism out loud to you. It makes you A LOT less nervous.
Good luck out there!