I so feel for you, KimTCL. Living with a borderline is like, well, horrible. I know, 'cause I am one!
Have you been friends/roomies long? I ask because, if it is your desire to stay with this friend, it might be good to "study" him.
Surprisingly, although borderlines are all over the place in their moods, behaviours, etc., we are also very predictable in that we have very set patterns on how we will react, and how deeply. We even experience "cycles" of behaviours (and these cycles could run for years - I have a 3-year cycle that I go through).
The toughest part is you always have to be on your toes to respond accordingly to the type of reaction of your roomie is displaying (I'm talking negative reactions only, here, because positive ones aren't really that tough to deal with!)
My b/f can "read" me quite well (which ticks me off to some degree, because it lessens the power of the drama I am creating to express "my" pain, but on the other hand, it also creates an atmosphere where I can come back to my senses, so to speak, alot quicker than if I were "allowed" to run amok with emotions).
After I found out he was studying me, I began studying him! I would watch how he reacted to certain things that would easily and consistently trigger me (like watching the news, reading a newspaper, certain subjects like religion/personal beliefs, what I would act like in line-ups, etc.) and I noticed that he would respond differently to each of these situations - all of which would start to defuse me (sometimes) rather than excite me further. Sometimes, he just had to leave because I would be so unreasonable or snotty or whiny (whatever), which in itself, made me take note of how I was behaving, as well.
I know you have your own problems to deal with and living with a borderline just adds more stress to your life (maybe too much depending on how agressive his BPD is).
What I have noticed that works the best is VERY STRONG BOUNDARIES - YOURS! And consistency in practicing those boundaries. (For instance: Your roomie always threatens to go off his meds. That must scare you to some degree, no? You could set a boundary that, should he decide to go ahead and do that, or if you realize that he has already done so, that he must move out immediately or vice-versa). Hint: borderlines are very co-dependent, it's unlikely he will actually go through with it, even though there will always be threats with doing
that , as well. Of course, the other biggie here is cooperation. If you don't have his cooperation (if he is not actively working on dealing with his illness(es), well, I just don't know what to say, except "RUN!"
What seems to control me best is knowing EXACTLY where I stand with someone, especially on issues or situations that are deeply important to the other person. I will always test to see how far I can push a person. I will always try to push and push and push. Knowing exactly where I stand with someone protects us both - physically, emotionally, mentally, and spritually.
Your roomie seems to bring you down alot. That's a drag. But know this, YOU have alot more power in this relationship than you realize. Do not let his dramatics tear you down. (Yeah, I know, always easier said than done...)
Have lots of tips for you on how to "control me!" Just ask!
AS