Should I keep trying?

I had a great relationship with my ex-girlfriend. We met because we were neighbors in the same townhouse community. We dated for 2.5 years, and talked several times about getting married. For about the past year, both of us were struggling with keeping our houses because of the economy. Eventually she had to short sell her place back in April of this year, and I moved her into an apartment not too far from where we lived. Then things changed. In a span of only a couple of weeks she went from talking about growing old together, to acting passive/aggresive (told me it was no big deal if I did not show up for her birthday), to picking a fight to end the relationship. During the fight she kept telling me that our relationship was going nowhere, and that I had become distant and rude to her as of late. After the fight, we did not talk for a couple of weeks, and then at the suggestion of some friends of ours who suggested the fight might have been a misunderstanding, I went and tried to talk to her to see if we could work things out. At first, she said yes she wanted to, but then became passive/aggresive again, and eventually asked me to meet her in a park near where I still live. In the park she gave me the break up speech, telling me we were not compatible, and that she did not want to hold me back from finding someone who would make me happy. I asked her why we were not compatible, and she could not give me an answer. She would basically say "because we aren't" or "I don't want to get out my laundry list". Then as we were walking away from where we were talking, she started crying. I asked her why, and she said because our relationship was ending. Then she turned to me and gave me a huge bear hug and would not let me go. Which seemed kind of odd considering she was breaking up with me. She then said "I don't want to be alone". Kind of strange. But still kept repeating "I just want you to be happy". I gave it a week and tried to go by her apartment and see her, and she accused me of stalking her, and made it sound like our relationship was horrible. I am confused, my friends are confused, I even talked to her family and they are confused. Her sister-in-law called me and basically asked "what happened?" She is not telling them anything more than what she told me about being incompatible and wanting me to be happy. The sister-in-law and the rest of her family did not even know that she had been fighting for over a year to keep her house. And they don't know that she hates where she lives right now, and thinks it is embarrasing to live in an apartment at her age. Unfortunately the sister-in-law did tell me that in my Ex's family once they make a decision, even a bad one, it is hard to to reason with them, to the point where she said "they can be stubborn as mules". She went from the most even-keeled woman I have ever met to someone who is angry, passive aggresive, to almost at one time, having what appeared to be a nervous breakdown. I have tried contacting her again through letters and text messages, but get the same response each time (i.e. we should both move on, things did not work out as we had hoped, eventually I find will find someone else who will make me happy). Not sure what to do right now? I have tried the subtle approach, almost thinking that one last face to face with her just to say I tried. I know what she is telling me is not the truth in regards to us being uncompatible.