Really, the only thing that you can really do is ignore them completely... I've gotten a few angry comments, and I know... It hurts. Unfortunately, that's the internet. If what you're saying is people are saying outright mean things, not perhaps constructive criticism, that's their fault, not yours. You really just need to feel confident in what you're doing, and not take what they're saying to heart. Thing is, on the internet, people can say whatever they want to, without being identified to anyone, and these people are the type to abuse these privileges. Just be confident in what you're doing, and listen to the good things people say about your work, and the positive outcomes. These people that will tromp on your stuff aren't worth listening to.