My brother has untreated BPD (won't accept diagnosis, won't do DBT, insists he has PTSD from arguments with my father which has led to lack of a relationship at this point with him and his ex-wife having cheated on him).

His BPD manifests itself in various ways. I do not mean to denigrate in any way those with BPD, it just seems that much of his behavior stems from this.

In his case (and some of this may not be as the result of BPD, but some other types of dx), if there's any disagreement or I don't do what he wants me to do (he's very controlling), he explodes into a rage, to the point that I feel like I have to walk on eggshells around him. He walks all over boundaries, and it has historically been very difficult for me to put up boundaries because he is so controlling, but doing so is on me, and I'm getting better at it.

Everyone in my family has called him 'abusive' at one time or another. I agree with this.

I moved to the state where he lives about 4 years ago. Before this, for many many years, I had very limited contact with him. He was abusive to me as teenagers and I wanted little to do with him, though it had been more of a passive not wanting to be around him, I never really thought about why. I felt protective of him in my mind.

In any case, since I moved here and have had regular contact with him, it has been a rollercoaster ride. When things are good between us, it's a pleasure to be around him. When we disagree about something, however small, it's horrific. To give an example, a few years ago I needed to buy a new car and he BLEW UP at me over the phone because I had decided to buy a car which wasn't amongst those he had recommended.

And there's so so so much more...

My point in writing all this, is that last night I finally wrote him an email saying that I want no more contact with him unless and until his behavior changes. It's only about a page long and is to the point. I also mention how he has blown up on my mother on many occasions (she's wheelchair-bound due to MS) and express my concern about that, but say it's up to them to work out their relationship between the two of them (I've gotten in the middle too many times; I'm learning...). I strongly encourage him to seek out therapy. I said I loved him.

I know it will hurt him. A lot. And I fear the fallout. Once when he was fighting with my father and stepmother over email, he drove 3 hours to their home and pounded on their door to talk to them in person. He then proceeded to blow up at them, scaring my stepmother in the process; she has said she's scared of him ever since.

I'm afraid he'll come pounding on my door as well. But my doors are locked and I won't let him in. I worry about this also because he has said many times that he doesn't want to deal with 'emotional' stuff via email, it has to be in person (unless he initiates such an email chain). But I won't see him in person because of his anger -I end up feeling intimidated and just can't express myself that way.

So the email is sent. My boundaries are set. It's actually possible he won't even read it, he's done this before when he suspects it's about emotional topics. but if he does, all hell could break lose. The last time I tried to end contact, his girlfriend, now wife, texted me that he had called her about it and that she jumped in her car in the middle of a work day to go where he was because she feared he would be so devastated he wouldn't be able to take it. But his reaction, his emotions and anger, are not my responsibility, or so people keep telling me, and it's beginning to sink in...