Changing your life is one thing. leaving behind everyone this guy knows personally and potentially could help sounds like a big mistake... especially with anxiety attacks and severe depression.
Changing habits/attitudes/etc. is important, but I'd try to do it incrementally - testing to see if these changes improve your experience, while focusing on maintaining and strengthening connections to things that you think make life easier/more enjoyable (could be friends/family or work or hobbies or ...)
[I'm not well versed in psychology, please take this as an idea to start your own research, and not a prescription of activity]
As in my reply above, I have in fact pretty much just done this. I went to South America last month and will be for a few months, volunteering. I left everything behind and rarely talk to anyone I know. I think I may have expected too much of myself, being able to handle this. Incremental sounds more sensible.