Dear Daytime Dreamer,
Perhaps you really are a good person.... perhaps what they see is what is there for them. Maybe you can't see what they see? Maybe looking at it from the possibility that they can see more than you might answer part of what is going on.
It really sounds like you aren't trusting yourself and all those other people can't be trusted either because you know the truth and they can't see it...or rather can't see through your self made facade?
I bet you aren't half as bad as you think you are...and even if you are bad... seems you recognize it and are wanting to change. Allow the possibility for you to be something in the middle between the two. Not perfect, but not unforgivable either. We all struggle with authenticity and how others see us, how we see ourselves.
Do find a therapist to talk to.