My thinking is that we tend to hold ourselves to a higher set of standards than the rest of the world. I know I do. For instance if I slack off in my work it's because I'm lazy. If anyone else I know slacks off, it's because they probably need a break. If I'm late for an event it's because I'm disorganized, unprepared and too stupid to set my alarm properly. If someone else is late, it's probably because they're having one of those days. If I take a sick day, it's because I'm weak; if someone else takes a sick day, it's probably because they're too sick to come in to work. See the pattern?

Even though we're aware of all these thoughts, getting them to go away takes a lot of work. I've hit the point where I just don't always have the energy to fend them off, so I try to let them wash over me instead. Just because you "hear" them doesn't mean you have to "listen". You're right, I don't know you personally, so you could be a horrible person (although, like Rohag said, unless you've committed any capital crimes recently then you're not that high up on my list of Truly Horrible People) but I'm going to go out on a limb and suggest that a lot of what you're thinking/feeling is due to depression, which I know from experience can seriously skew our self-evaluations. In the meantime, is there anything you can do to actively contradict these thoughts? Do a favour for a friend, volunteer, spend time with your family, whatever falls within the bounds of what you expect a good person would do. It might help you ignore the depression's lies if you have tangible evidence of your "goodness".