Feeling like shit over a break-up...and deservedly so, I guess

I'm a 43 year old divorced guy with a VERY bright 9 year old daughter who had been dating a 37 year old divorced woman until a few months ago. Her kids have problems -- the son is 17 and autistic and the daughter is 14 and slow learning/learning disabled. I met the woman through a social club we both belonged to. Anyway, we began dating and I dumped her after a few months because I thought she was too uninteresting and uncommunicative compared to the two other women I was dating at the time. There's a huge difference in our education level and job backgrounds as well -- she has a high school education and has always worked low-paying, blue collar jobs; I have a Bachelor's degree and have worked mostly medium-income, white collar jobs. Anyways, after the other two women panned out and fell through, I started thinking that maybe this woman's simplicity and good-naturedness wasn't so bad after all. So I saw her at a social club event again and managed to talk her into going out with me again.

It went great for the first few months. I treated her like a queen -- fancy dinners, jewelry for her birthday, flowers, little surprise gifts, etc. Sex was good too. The only problem was that she was constantly bitching about how she went to a technical college for a one-year diploma program in Medical coding to better her economic situation, but couldn't find a job in it (frankly, I don't think she was trying as hard as she could have been). I tried to show her how to construct a good resume and how to job network and all that stuff. Then, suddenly, I started having problems at my job and began becoming very depressed. I tend to take stuff like that pretty seriously because I have manic depression (or bi-polar disorder), but usually I can control it pretty well. But then she decided she couldn't handle my mood swings and dumped me right before the holidays started (the day before Thanksgiving, in fact).

We stayed apart from each other until January this year, when we ran into each other at a basketball game and reignited the flame. We started all over again, but then she began this flip-flopping attitude. One week it was "I really love you and want to live with you and eventually get married", the next week it was "I just want to be friends" and then back again. Then we would take a weekend getaway trip together and she'd tell me "I feel so safe and secure when I'm with you". I even gave her a book to read about bi-polar disorder and how couples deal with it and work through episodes of it, thinking it would enlighten her and that she would be sympathetic because of the problems her kids have. Instead, it pushed her further away. Then it was back to the flip-flopping attitude again. Finally, she said "I just want to be friends" and seemed to mean it. I tried to respect her wishes, but with all the things that didn't make sense to me, I tried numerous times to e-mail her and ask her to explain certain things in her actions and contradictions that just didn't make sense to me. I told her that once she would explain these things to me, then I could ease my mind and really be her friend. But the next thing I know, she e-mails me and says "I'm tired of being interrogated by you like a trial attorney", and she slaps a harassment restraining order on me ! And to top it off, she tells the social club we both belonged to about the restraining order, and they kick me out of it !!

Besides the obvious (not doing the e-mails asking a chick to explain her actions), what else can I really learn from this experience not to choose a woman like this again ? Or, what should be the most telling warning signs I can pick up from this experience ?