I just dont believe it was all about....
--spoilers--
I just don't believe that all of the thing was about Troy and Britney, I think that it did have somewhat to do with getting back at Mr. Anderson.
Even though she said that all of it had to do with Troy at the end, it wasn't all about Troy.
I believe that she did like Britney and Ronda..even though she was pretty sick.
I think she may have been thinking of a way to get backk at Britney about Troy, but I really don't think she sat there and planned it out. I think it got out of control, and because she was crazed she didn't care all that much.
I believe that Ronda's suicide really did affect her, and I believe that at the end she was really unhappy. One for being so upset to try to take revenge on Britney for Troy and two because she tried to blame it all on Britney and Troy, and three because she was sad because of all that happened with the incident and with her whole life.
~But that's just me~