Why Is It So Hard To Let Go

I've had a friend of over ten years that I recently broke up with. It's been a very difficult time for me as a result. She was someone I really cared for and now we can barely speak to one another. It all started in January of this year. She was with her boyfriend at the time who she really didn't want to be with any longer according to her. At the time we were talking over MySpace but she gave me her cell number and we started talking over the phone. Now I had not seen her in a few years. I've know her since the fifth grade but our freshmen year of high school she transfered and I transfered so we lost contact with each other. I went to culinary school and finally came back home. I found her on MySpace and we began chatting. We let's get back to January. Like I said, at the time she was unhappy with her situation and wanted out. The more and more we talked, the closer we got. Well, finally one day she told me that she had feelings for me and that she no longer wanted to be with him, instead she wanted to be with me. Well, I have to be honest, I wasn't going to turn her down. I was very attracted her and cared for as a friend. I had always hoped that our paths would cross and maybe someday we could date. Well, needless to say, two days after that conversation she broke up with him and then a few days later, she got back together with him. Well, I was hurt by it all. I mean, why tell me that you want to be with me if you are going to go back to him? Well, I let her go. I got back to my life as it had been before all of that talk had started. Well a few months later, she breaks up with him and we start talking again. I had not spoken to her in months as a result of what she did. Once again the subject of us dating came up. I was hesitant again, but not for the same reasons. I didn't want to get hurt again by her and I thought that she might need some time to heal before getting involved with me. For me, I knew that I did not want to be any kind of rebound for her. She assured me that she was ok so we preceded to carry on with our relationship. We went out, talked for hours on the phone every night. I became very attached to her, basically I feel in love with her. You may be wondering how that could happen so soon, well you are not alone. I wondered that myself, but I can honestly say that I did/do love her. Well a few weeks went by, things seemed fine. I spent the day with her at her house. We hung out, cuddled, held hands and I kissed her good-bye. We had a great time that day. Well two days later, things go from good to bad real quickly. We broke up. I had never been more hurt. I was very confused as to what had happened. Well, a few days later she and her ex were hanging out with some of his friends who are a couple and something happened that night. I can't go into detail but needless to say she called me needing to talk to someone. Well, I managed to pull her through the situation and we were talking for a while but once again things got bad to the point where she pretty much has shut me out of her life and now is talking to her ex and those people again. She told me so many times that she was done with those people, only to find herself talking to them again. It hurts so bad that I of all people have been pushed away after everything I've done for her. All the times she needed someone, I was there. I feel betrayed and down right, disrespected. Yet, even after the way she has done me, I can't help but love her. I can't let her go just yet. One of the reason is, she won't tell me what is really going on with her. I need some closure to the issue and I don't want to walk away without an explaination. Am I wrong for feeling like this? Should I just walk away from it all and just let her continue downward spiral? Does love just make you this stupid?