My heart goes out to you. I have the exact same problem and it's not just with work. I've been unable to write long form since the beginning of high school. Funnily enough I managed to scrape through most of an English degree program until I dropped out in the fourth year.

IM is usually ok, unless I expect to be criticized.

My remote fiasco is pretty similar to yours. Eventually it got cut from a full time job to an hour a month maintenance gig. I ended it when I started an in-office job and supposedly sign again for easier paperwork. I've been putting it off for like 3 months and old boss doesn't even send reminders anymore.

Current job is very scrummy, very social. Coworkers are a chair roll away, so no email. Right now there's a lot of work and scarcely have time to go inside my head. I hope it helps, I really do.