Lost cause, mate. I get some sort of confidence/buzz through running and stuff, but it's really not going to carry over into other aspects of my life. I can fake it enough just to get by, as in work and socialise.
I do relates to a bit of what you are saying. Again I'm not going into my life details either. It's the wrong forum for a start And I don't find it that helpful, dwelling on my perceived failures or what you will. But one thing to maybe try, when you are having particularly negative thoughts about yourself, Try deliberately thinking the opposite. Thinking, no actually what if I am not shit, what if I say I am not this caricature. I am objectively good at some things, I can talk to people, they don't in the main, run away or throw up.
I know it sounds like some half arsed CBT thing. But it's the only way IME of smashing through it. Do stuff you are good at and enjoy, look around, get interested in something, Get out of that headspace.
It doesn't work all the time, it can be hard work but what else is there.