If only I had a proffesional writer to properly portray this drama

Okay funadvice, I’m in a real pickle. I met this girl in November, at the time we were just really good friends and I was kind of attracted to her. We talked more and more and eventually we became VERY close. Around February we hit the peak of our friendship, and I finally decided to ask her out and tell her how I felt about her. She told me I was too late because she used to like me but now she thinks of me as a “brother figure”. I was crushed. She reassured me that at least we were still best friends, but after the night I told her how I felt our relationship began going downhill.

 We couldn't really talk to each other the same way we could before, and we were causing a lot of stress in our group of friends (four of us always hang out, me and this girl, and then a friend of mine and his girlfriend, who is also a very good friend of mine and the girl I like). By March break I realized that I loved her, and I use that word very sparsely, I believe it is overused. So I really mean it. Eventually problems were arising in our group because of the way I felt about this girl, we'll call her P from now on. I tried to hide my feelings the best I could, but she always did things to bring them out, such as flirting with other guys in front of me (it turns out that she actually did this on purpose, because she hates the fact that I like her). 
    So eventually, all the members of my group of friends decided to exile me from the group, bon voyage. They felt that it would be better for the group if I simply wasn't there. Apparently P was afraid to hurt me (which she constantly did purposely). So after a while we patched things up, and I'm now closer than ever with all the members of my group other than P. Now P has been ditching the group to hang out with other friends, and they have caused her to act in a much bitchier way than usual. She's best friends with the other girl in our group, who I'll refer to as T. So P has been hurting T a lot by ditching us and doing all her bitchy things. 
    Now it's come to the point where T thinks we should leave P, because T really can't take all this stress anymore. And I don't blame her, my problem is that I really don't want to just let their friendship completely die, they were so close. Another problem is that I still love P a lot, and I'm not sure if I can just quit on her, she is like life. To quit on her is to die. But to continue trying with her is to live an extended life of misery. Neither of those is very good at all. I want to do what I can to make everyone as happy as possible. What should I do?