Hi Zen,
I do that a lot, too. It really sucks when you're your own worst enemy because the people you love and looked up to taught you how to become that to yourself so well.
When I am aware of that going on, I try to find the voice inside that protects and defends me and I bring her up to battle it out with the negative and mean voice. She's pretty strong and she usually kicks the meanie voice's butt and it goes away. You need to get in touch with your inner kick the negative voice's butt voice.
((((((((((Zen)))))))))))