1) People are often busy or they are dealing with their own problems. Just because they aren't talking to you doesn't mean they've burned bridges with you. That is always a foolish assumption, and frankly I think it is one of your biggest challenges. A part of you seems hellbent on making these assumptions and turning them into self-fulfilling prophecies.
I talk to the people in that group in fits and starts. Some people I may have an intense conversation with over a day or two, then I don't talk to them again for a year. It doesn't mean we don't like one another. We just have other things going on. Remember - I have not physically met a single person in that group. Most of my interactions with them are conducted on Medium itself, with occasional splutterings in the group (such as the recent discussions on Danielle's post about male/female following quotas).
2) I understand and have much sympathy. But don't let that be an excuse. I forced myself to interact on Medium and in the group, as I know that drives traffic to my articles. But in the process of doing so, I have become genuinely fond of people in that group, and enjoy our banter a great deal.
3) See point 1, really, with added sympathy for your ongoing mental health challenges.
8-10 pieces in a day is excellent by the way. I often don't manage that much. :)