Pushed to the Brink

I've said this before, I'll re-state this for the record:

I fucking HATE stupid people.

Got it? K. I'll leave names out of this, since I've been asked to do so, but let me bounce this off y'all just to make sure I'm not overstepping my bounds being just flabbergasted as appalled.

So, I have a friend, with whom I have spent nearly day this summer. She is a wonderful person, to whom I had opened myself up genuinely. She and I were the two people around whom we could really be ourselves, no holds barred. We've been friends for years, since my junior year of college.
Well, ok, she's got two minor flaws which seem to be the cause of several recurring issues in her life, and mine too I guess because I care about her so deeply and hate seeing her hurt.
1) She has a thing for men that do bad, bad things.
2) She has a thing for dating drug dealers, or people who are very very close to hard drugs.

So, a couple three weeks ago she stays the night at my house after a long night partying with some friends. The next morning, I asked her if she wanted to date until I take off for Japan, cause after all, we spend every day together, we might as well. That day was the last I saw or heard of her for a week.
Well, just prior to that, she had finally gotten a hold of the number for her ex-dating partner's coke dealer. He was not ok with giving her the number cause he was afraid that as soon as he did, she would disappear forever from his life. We both joked about this, because their friendship was independent of doing coke.

Man, turns out I was wrong on a number of things there. So a week later, I get a call from her, and she explains to me that she has been locked up in the bedroom with none other than the dealer, and that they're a thing now, and sorta had been even before I had asked her what I did. Oh, and her ex hates her now, and they don't talk anymore. So basically, he was right about why he didn't want to give her his number.

Well wait, this gets better. Her ex from like a year ago, see, they broke up because she had him thrown in jail for shoving her into a wall, and then again when he violated his parole and/or restraining order. There was a lot, a LOT of animosity between them. I was around when she finally told him that she never wanted to speak to him ever again. I watched her cry night after night dealing with his verbal abuse, and the way he made her feel about herself. And I watched her time and time again slip, and either hang out, or fool around with, or talk to this guy and re-start all the crap she was trying to leave behind.

Oh, on an aside, what two things can you tell me about this guy?

So, she diappears for a couple weeks for this new guy, and then I get a call from her yesterday with some news. Her ex from a year ago showed up at her door the night before. Dropped to one knee, and proposed to her.

And she said yes.

What in the Holy name of Christ were you thinking?! What in the FUCK gave you the brilliant idea that MARRYING this guy would be a GOOD idea?!

Now, I have a degree in psychology. I know why she thinks this is a good idea. I understand the nature of abuse, I know what it does to people, I know about the learned helplessness people come to have, I know about the need to be needed so desperately as to go to extremes like abuse to keep someone. I know that people feel like they can help someone, or that they don't deserve better than that, or even that they like the abuse.

But what I don't understand I guess, or what hurts me the most, is that she's committed herself to a life which can never get better. I care about her deeply, I've been there for her through some crazy shit, as has she for me, there have been so many nights sitting there listening to her tell me how she has to clean up her life and make better choices and how we're here for each other. And to see all that thrown out the window, ignored, and for what?

How am I supposed to feel about that? How can I be there for someone who dives headfirst into not only a life of potential misery, but stabs me in the back to do it? Should I be happy I dodged a bullet and write it off? I mean, I'm leaving pretty soon, and theoretically, that could be it. I could walk away from it all and never think about it twice....but how can I just abondon someone who is doing something so clearly self destructive?

I guess it's not my life, and not my set of decisions to make, but how do you be there for someone like this?