I made a post here the other day and deleted it because i got nervous- the person i'm referring to uses reddit and I don't want them to possibly see these posts, but I'm in desperate need of some insight.

TL;DR i recently saw their discharge papers from 2 mental hospitals they've stayed at recently, and none of them have the disorders they claim they have, but, they do say that they have BPD. This person is faking having Dissociative Identity Disorder and it's frustrating to live with, as someone who was professionally diagnosed with DID 4 years ago. I'm coming from a sympathetic standpoint, because I also have BPD. Diagnosed in 2015.

Anyway. This person gets super defeated when I do anything that isn't directly interacting with them. I can be somewhat busy, I work from home and often times have to spend perhaps 15 - 20 minutes uninterrupted in order to focus on a task. This person can't handle my attention being off of them for more than a few moments. When I tell them that they are talking a bit too much for what I can handle at the moment (for example, right after waking up), they tear up and get upset and say "ok, I'll try to not talk anymore."

Everything is a game of theatrics to this person- everything is either the best thing they've ever seen, or the absolute worst. After that it just becomes a games of tears, blowing everything out of proportion, and bringing up things I did months or weeks ago because they're defensive and want to hurt my feelings, because something I said accidentally hurt theirs. Something always hurts their feelings, and I always, always have to spend hours apologizing to them and talking them down out of these fits.

They can't spend time alone, or even give me time to type at my computer without some kind of catastrophe happening. The thing I can't stand the most is when I'm watching a video on my phone, or smiling at something that they can't see, they'll sigh and get teary eyed and say "i'm just so alone. :/ I'm so lonely." I can't stand when they tell me they feel "alone" when i've been in the same room with them and interacting with them for hours. it's really frustrating because they're trying to guilt me to do more, but i'm at the edge of my rope.

this person has no other friends and uses me and me alone for their social network AND a therapist. i can't handle being a partner, a therapist, a best friend, a sibling.... i'm this person's entire world and i'm suffocating. i 

How do I get it across to this person that these behaviors are super manipulative, and that I need space? I don't have any freedom of thought or activity unless they're involved. The only times I can do stuff like this is when they're asleep.

Any advice helps.