Just a Phase?

First of all, I am fifteen years old. When I was twelve, most of the people I knew left the school we were attending, while me and the few people that were there from previous years basically freaked out. This is when I met kaitlyn and started this co-dependent relationship thats been going on for sometime now. After about six months of dating, my brother had exams so he couldn't come to hawaii with me and my parents. We couldn't refund our tickets, so we decided to take her. That is by far the realest and most intoxicating experience i've ever gone through. We dated for at least a year afterwards. We were still going to the same school, and we still spent all of our time with each other. The drama had really started to pile on, we started to fight. Quite frankly it got boring, it felt like we were married and we were only 13. We went out eventually I guess because there was no one else, and while we were dating she met this guy. I'll talk about him in a second. After that last year in middle school, we went to different schools. We still talked to each other everyday, and were still extremely close. She had started going out with that guy I mentioned. She'd gone through a couple boyfriends after we had split up "for good", but this guy was different. She told me she was in love with him. Naturally, that had a huge impact on me. I was lost and had no clue what to do. Once again I was going to a school where I barely knew anybody, and she really was my only real friend. I would've been ok if she didn't start treating me completely different, as if we were going out and just broke up. There was one friend we had from middle school whose house we would go over to. Kaitlyn and I got stoned and made out. She felt guilty, told the guy, and he broke up with her. I blamed myself for breaking them up and making her so depressed. As time went by, although we remained best friends, she became more and more obsessed over him. Although it killed me, we would talk about him. A year went by where it constantly stayed like this, and we constantly fought. We were friends with benefits, which confused things even more. I want to say it was like we were married and she was always talking to me about wanting to have an affair. We told each other "i love you," before we went to sleep every night. I came to her school mainly to be with her, but for a socially better position overall. And I got sucked into her click, I hung out with all of her friends, we all hung out together. The fights got worse, and she was mainly getting fed up with me. I saw how depressed and lonely she was, and although I always knew it was because of him and there was nothing I could do about it, I wanted to take her out of the hole she was in, and the whole she continues to be in now. Time passed, I started to think maybe we really could work it out, I could get her mind off of him. I helped her through everything, all of her problems. I started to get aggrivated and it eventually became only me that was starting the fights. I couldn't take her out of that hole...No matter what I did. We started to have more and more fun with each other and I thought maybe we could start a real relationship back up again. There were no longer real fights...It became constructive criticism. But she still didn't want to be with me, she wanted to be with that guy. This is when I started to realize how bad of a guy this is and how its a very good thing that I split them up. He does all kinds of drugs, he treats women like crap, and she still wanted to be with him. She knew he didn't care about her but she was still obsessed, in fact that might be while she still is obsessed with him. Even though I knew she was obsessed with him and was getting fed up with me telling her how I felt about all of this, I still tried to hang on. I knew we needed a break at the least, but when I tried to just break off from her altogether she started getting pissed at me. Of course over all this time I was dating other girls, and they treated me like crap. I got cheated on, nobody my age was mature enough for me. So, she started getting pissed at me and I kept talking to her everyday. Things had changed, she never tried to really talk to me. It was just normal conversation...But sometimes she had to come to me, because all of her friends were abandoning her due to her constant depression.This guy remained one of her fairly close friends, even though he often ignored her at school. Maybe a week after this I figured out she lost her virginity to him about a month ago. After this had happened, and before I figured out what had happened, she was still telling me she loved me every night. We would talk about our situation every now and then, she told me we had true love. But, she decided to stop being friends with benefits with me because she claimed I couldn't handle it and she was getting her feelings confused. And in turn, she became friends with benefits with him. The guy was on extasy when they had sex, I don't know why she did it. It blew my mind...It's literally put me on the verge on insanity. I always knew I was going to lose my virginity to her, there was never a doubt in my mind. And we had talked about it while back, and she said if she did have sex with another guy it would be very unfair to me. She knew this would rip me apart, but she says she never thought twice about it. She says she doesn't regret it, even though its only made her more obsessed with a guy that doesn't care about her. I explained all this to her, wrote her a very long explanation of our relationship, why we fought, and why it was very unfair to me and herself to lose her virginity to him. She agreed with everything, she said she understood, but she still doesn't regret it. Why? I have no clue. I really have been ripped apart over this, and i'm glad this is online and nobody knows who I am so I can fully explain whats going on with me. I'm having really bad nightmares. Theres a nightmare where i'm in the middle of this big house as its burning to the ground. Its filled with people I know, all burning to death. Theres another dream where she's in the back of his car with all of our friends, i'm lying on the ground and they're all laughing at me as they drive off. I'm breaking down...I didn't go to school the day after she told me. I layed in my bed, listen to bob marley, and cried all day. Alll day. And that was when I realized I have to stop talking to her altogether, i'm not gonna let her do this to me. I've felt like we were one person for so long. She's made me pick apart every little problem with myself and even though i've done my best to fix it, she doesn't want me. Even if she doesn't want me at all, why would she do this to me? She says she loves me more than she loves herself, but she doesn't regret it at all. She wouldn't let me break off completely from her even though she's always said it would be a good idea. Can anybody explain to me whats going on in her head? Is it a stupid teenage mindset, a sense for adventure, finding new and exciting things and leaving the past behind? It doesn't make sense...We've always known we were going to get back together some day, we'd give little hints to each other that things could and will change. So why would she completely destroy this, I can't even look her in the eye anymore. I don't think i'm ever going to be able to talk to her again, even though I want to so bad. I want to talk to her and help her through this crappy time shes going through...I've always tried to help her, and in turn I think I never helped myself. I think she's forcing me to hate her but I don't know why. I haven't smothered her...We've always been there for each other. She said she knew it would break me if I ever found out...But she doesn't regret it at all. Heh ok sorry for the long post, I don't even think half of you bothered to read to this point.