Hi! I believe I can be of help with this issue.
First, let me say I am very glad that you have dealt with your situation, even if not completely with your feelings, and that you are moving on in your life. That's wonderful. It makes answering your question much easier for me and not as heavy on the heart because I know that you have taken the steps to not get more entangled. So your question and my answer can take the form more of trying to understand something so tragic and being able to sigh about it but knowing you're going to move on.
You've done extensive reading on passive aggressive disorder (PAD). The problem with it diagnostically, as you know, is that it is unclear exactly what we're dealing with. Everyone now pretty much agrees it's too amorphous to be a distinct personality disorder on its own; it has too many features of other disorders. However, it does not mimic completely any other personality disorder and so can't quite be dismissed as part of some other disorder. The point?
PAD is somewhere on the spectrum of personality disorders. There's no agreement EXACTLY where, but there is no doubt that what you experienced was loving someone who has a personality disorder. So what does that tell you?
It tells you something extremely important. It tells you that whatever it is and whatever the cause, it is not going to go away in the near term and there are no medications to treat it directly. The causes are not known, period. There is much speculation about overbearing parents, dysfunctional parents (alcoholic, etc.). But these are not based on research but on logical constructs: it makes sense that someone would develop this way if their parents were this way...
So, the truth of personality disorders is that they are intractable. Imagine what makes up your personality. Even something as rudimentary as, let's say, saying "umm" when speaking can be torturous to try to change. It doesn't bother the person so much; to the one who says umm, it's natural and part of who he is. To listeners it can be extremely distracting. Now, instead of something as rudimentary as saying "umm" you take a part of a person's being that's BEEN a part of how he interacts with the world for as long as he can pretty much remember, what do we have? Well, most of the time, it's as natural to be passive aggressive for him as to say "umm" to that other person. He doesn't even know it.
And this is true of all personality disorders to a very great extent. A narcissist, for example, doesn't know he's a narcissist. He just knows that he is living his life. That in his life he is like the sun and everyone else is like the moon, there to reflect his needs and joys and wants, is just how the world works, not an abnormality. Well, with PAD, your friend just knew that this is how the world works and how he survives in it.
So wanting to love him for his good parts is like wanting to love only part of who he is. He cannot be separated from his PAD. He is a whole being. And he will have to deal with his problem perhaps the rest of his life. Well, most likely the rest of his life.
But you can go on and have a wonderful rest of your life!
Please remember to click the green accept button. Feel free to continue the discussion; my goal is to get you the best answers possible. Bonuses are always appreciated! If I can be of further help with any issue, just put "for Dr. Mark" in the front of your new question, and I'll be the one to answer it. All the best, XXXXX XXXXX