Book:
I Had A Black Dog: made me realise I was depressed.
Advice from therapist: letting your mind replay traumatic events from the past means you are re-living them, re-experiencing them.
Info from a book (can't remember the name): treat your thoughts like a radio playing in the background. You don't have to take heed of it. After a while you will stop getting annoyed by it.
Quote: "you are not your thoughts"