The Power of Now by Eckhart Tolle is brilliant. You can listen to him read it on YouTube, free.
He got to the stage where he was suicidal, he said he 'couldn't live with himself anymore', and realised there must be two of him. One self, and one who couldn't bear the self. Upon realising this, the critical self dropped away, and he's been as happy as Larry (well, probably happier) ever since.
I've had a much quieter inner critic since I read the book, and I do just chuckle at it now, much as I would any other critic. Don't believe everything you think.