Feel guilty? That's your frontolimbic network at work! That part of your brain is responsible for the "it's all my fault" feeling:
In the 22 individuals with no family or personal history of depression that made up the control group, statements designed to induce feelings of personal blame caused brain activation in a predictable network of brain regions working together: The regions that make up the frontolimbic network -- a set of primitive structures in the brain that help us process and respond to strong emotions -- worked hand-in-glove with a structure called the anterior temporal lobe.
Melissa Healy of LA Times' Booster Shots has the story that may make you feel guilty if you skipped it: Link