Feeling like a horrible person.

For the last few months, I have had this horrible feeling that I am pathetic. That everyone hates me. That I'm worthless. That I'm just a child.
It does not let me concentrate because it is all that I think about. It does not let me socialize because I think everyone hates me already.It does not let me do the things I enjoy because I think they are a waste of time or something I should not be doing. It does not let me work on my personal projects because what if I make something bad? It completely takes over my thoughts.
I know these fears are irrational. I know that I should just ignore them. But I just can't get rid of it.
I cannot function like this.
So... Any tips on how to deal with it?

Moved to Self-Esteem, with a shadow link left in General Anxiety to follow here