Bravo,
That's the best thing to do. End it. Walk away and don't look back. People like her use their depression and threats of harm to themselves to keep people around them. It's like reverse spouse abuse. Where a guy usually tells a woman "You leave me, and I'll kill you" or "If I can't have you, no one will", women (or men) with this illness will threaten to kill themselves everytime you try to walk away. You get put in a situation where your choice is stay and be miserable forever, or walk away and have your consciounce eat at you. She knows you're a good person and uses that to try to keep you with her. The fact that you care, and feel bad shows you are a good person, but it doesn't mean you love her....but she will tell you otherwise. You did the right thing. Let it go. Live and learn. She'll find someone else to blame for all of her failings.

BUT, if you're next 3-4 relationships do the same thing, you might wanna get some counseling...it MIGHT be you!!! LOL!!!