Welcome Ton: I'm so very sorry about the situation with your son. Do you know how long he has been off his antidepressants? Some people go off them because of certain side effects. Has he ever had any therapy?
Are you doing anything to take care of yourself and help manage your stress? Loving him from a distance sounds like a safe approach.
You might find this thread on Radical Acceptance helpful to support your current situation:
https://bpdfamily.com/message_board/index.php?topic=90041.0;allAt the upper right of this post, there are a lot of links to lessons that you might find helpful. Reading about
FOG, and
BOUNDARIES could be a good place to start reading.