You know, I can really relate with a lot of what you've been writing here. My self-criticism is a huge monster as well and it's torturing me slowly from the inside.
Sometimes (or a lot of times) all other people can see is the result of that torturous internal negociation with the voice of the "never good enough". The voice is the critic, but it's plugged into this invisible and hateful belief about myself.
Maybe you can relate...Hope not, in a way..

I want to believe that this will get better too, that the monster will fade some day. The truth is, it's been with me since the beginning maybe, but its voice varied in intensity over time.
Maybe we can learn to live with it.
Though right now all I want is to kill it somehow.

Maintaining contact and making friends online seems hard for me too, maybe also because of the constant self criticism and fear of dissapointing people. So here the key would probably be accepting that I am okay, abandoning the "there is inherently something wrong with me" belief..But this one takes time. I think. I've tried, was working on it but I feel that now I'm back at square one. Or maybe I'm close to solving it...I don't know.

So yeah, also just want to say, feel free to write to me if you'd like.