Please love, you're not a freak, you struggle with social stuff. Lots and lots and lots of us do.
I know you beat yourself up for "failing" the interview, but don't give up, keep going and you will get better at them.
Do you have a friend or someone who could mock interview you? Ask you tricky questions etc? So you get used to answering likely questions and not so likely ones?
Cbt is good, but it's only good when you're calm and able to reflect. It's not good for calming you, that has to be a different strategy.
If I were you, I'd go back to the GP, perhaps see someone else, could you find out from the receptionist who is best for anxiety issues? Some gps have special interests in subjects so are able to advise different solutions.
Don't give up! Have you tried rescue remedy? That helps me when I'm anxious
I used to have agoraphobia, mildly but it had its excruciating moments. Rescue remedy was how I managed to give myself the feeling that I could cope with being outdoors, looking at people, talking to people.
It's a hard slog, but I know you can do it.