I wonder; were you sexually abused as a child?. To be so afraid of people is not normal, but is normal for people who have had a trauma at some time in their life.
As children we accept everything as normal, so we cannot defend ourselves from being influenced. Then a learned behavior and way of thinking or perception of ourselves becomes set. We are all brain washed in away because of our chilhood experience. From what you say I detect that you have a guilt complex and being around other people brings it out, which is why people make you nervous.
You remind me of myself as a teenager. I was abused sexually( not by a family member).I suffered from social phobia like you. I had a stammer which I was very embarressed about and as a result I had no friends as such. Like you I did not trust people and I would go out of my way to avoid people.People did think I was a snob, which just added to everything and my problem of self persecution.
I could go on , but I may be barking up the wrong tree. You can email me if you like.