There are many people that suffer from this. I think many of us are not wired for modern society.

It's called agoraphobia. The only thing I can say is if u want to change, u must force urself to go out and be among ppl and places until it becomes comfortable. If u don't make that effort, it won't change. Best!

I've had similar anxieties, about traveling. "What if I never make it back?" - farfetched stuff like that. Seek counseling and find something else to occupy your mind. Build model airplanes, watch TV, go the mall, exercise, whatever it takes.

Social anxiety has a lot of medicine choices. Hundreds actually.
I assume you have sought medical attention for this correct?

There are so many medicines to deal anxiety.

Take up boxing it will give you the confidence to handle anything