I overreact to any social contact

I brood about a single non-hello from a store clerk for weeks. I go through great lengths to avoid people; for example, I will walk around an entire city block rather than pass someone I know even slightly. No one is allowed in my house, and I won't get in situations that would invite visits from anyone. Human contact is painful and I have a very low tolerance for pain. It is painful because no two people can interact without conflict. Social contact and the resulting emotions overwhelm me. I am extremely reactive in a hateful way to any two or more people talking in hushed voices while staring at me and feel 'done to' by others. I also feel rage when anyone invades the careful boundaries I have erected around me. Paradoxically, even though my solitude is by choice, I feel hurt when people dislike me or ignore me. Their behavior makes me hate them even more.