I agree with FuzzyBear. You aren't a 'bad person' or you wouldn't feel any guilt. I struggle with this sometimes (no religion or afterlife here either), but I have to remember that I was ill. I try harder and know better now, and I wouldn't act in that way again, hopefully. You ARE a GOOD person. Next time you think about the negatives, try and think of a positive thing you've done to combat it.