My therapist actually just floated the possibility that I have AvPD in our last session, and while I haven't been formally diagnosed, it fits like a glove and would explain a lot. Without getting into too many details, I'm in a pretty similar situation to you. In my case, I had a fairly normal childhood--didn't deal with it until I suffered through years of severe untreated depression as a teen--and while I don't honestly believe I'll ever get back to my original level of functioning, I still think I can find happiness even if it'll look a lot different than I once imagined. I'm also down to basically two friends (my childhood best friend and his partner) who I will maybe exchange messages with a few times a month if I'm not in the midst of a months-long ghosting spell. It's important to acknowledge small victories (e.g. I used to basically never answer the phone up until a few years ago, and now I almost never let friends and family go to voicemail).

I can definitely empathize with feeling like a leech or a waste--it's a constant battle for me. I think leftist politics have helped me a lot with this, actually, since I realized that a lot of the people I know who get a lot of praise and are supposedly "successful" and "productive" are actively making the world a worse place: investment bankers, management consultants, insurance executives, corporate lawyers, defense contractors, etc.. I at least can take some solace in knowing that I do make a small but positive difference in my tiny sphere of influence and don't leave much of an impact otherwise. Shifting perspectives can be helpful: if you imagine yourself as a friend with the same disability, would you berate them or call them a waste?

My focus right now is to try to find joy in my interests and work on basic personal care to improve my quality of life. Progress can seem glacial, but the process of learning an instrument and understanding & making music has brought some meaning back to my life and given me something to value about myself besides fitting into a societal mold. I know this isn't accessible to everyone, but I've also found group therapy to be helpful, since I can talk with peers who are also going through the same struggles. It's nice because I can be a mentor to some of the younger folks, get some social contact with people who aren't going to judge me, and remind myself that there are other people in this world who care about me.

And yeah, I want to acknowledge how twisted it is to want to form deep bonds with people while being pathologically terrified of the same and doing everything to prevent that from actually happening. Like, with my childhood best friend, there have been multiple times where I've actively hoped that this time would be the last straw so he would finally give up on me and be rid of this nuisance in his life. How fucked up is that? Thanks brain, very cool!

Sorry, I feel like this took on a bit of a lecturing tone which wasn't my original intention. I just want to remind you that no matter what messages you may get from our fucked-up society, you have intrinsic value as a person and your disorder is not your fault.