Is this right???

Hmm, wow I never thought of that, I always just figured Mima was the crazy one...must watch movie again to figure it out...

I partly agree with you that Rumi didnt want Mima to quit her image as a Pop Idol. Yet bear in mind that she clearly knows that Mima has chosen to road to become an actress who acts in a rape scene and poses nude photos, not a singer any more. That's why she is "infurious" with Mima. In "Perfect Blue", Rumi, as a spectator in Mima's performance (no matter she is a singer or an actress), she gradually identifies herself as Mima.

As we know that the spectators in the film are all MEN except Rumi. Her fans are all men during her singing performance. The ones who watch and talk about "Double Bind" and read the magazine with Mima's nude photos are all MEN. Rumi probably thinks "a pure Mima" is so much much better than "a filthy woman with tarnished reputation" that she wants Mima the Pop idol back and gets rid of Mima the actress, begins identifying herself as Mima the Pop idol...

Btw, anime will definitety be better live-action film with regards to this psyhcological thriller. as an animated film, it's more "Believable", more "Real" than real live-action film, at least. I Love it soooooooooooo much!

I had to watch over the movie a couple times to get all the information I could straight and here is what I gathered:

-Rumi (Mimara's manager almost) used to be in the pop singer business herself. In one scene Rumi is talking to one of Mima's representatives in the office of the movie set and he says to her something to the effect of "things are alot different since Rumi was a pop idol"
-Rumi was heartbroken that Mima decided to accept the role as a rape victim because she was worried what her fans would think of her and her reputation.
-Rumi hired a hitman, the "stocker" if it were that Mima had always saw on her set to kill Mima and people involved in the drama series "double Bind." Rumi did this because she started to confuse illusions with reality (as did Mima and the stocker, as I'll later mention) and believed that she, herself, was in fact the real Mima and that Mima (the actual Mima who played on the drama series) was an imposter and was tarnishing her good name.
-Rumi talked to the "stocker" through e-mail and told him that she in fact was the real Mima and that this "imposter" was interfering with her life and getting in her way. She assured the stocker that the real Mima would never do such scenes and degrade herself as this "imposter" did (in both the drama series and magazines). The stocker believed what she said to be true and started writing entries on a website he created called "Mima's Room" and wrote in what Rumi told him to. He told Rumi that he'd get rid of her.
-The stocker had never seen the actual person he was recieving e-mails from claiming to be the real Mimara, otherwise, of course, he'd know that she, indeed was the imposter. The scene where he is typing at the computer desk with Mima beside him in her skirt-suit, was a figment of his imagination he interpreted as reality.
-The movie was really confusing because it was hard to interpret whose illusions you were seeing whether it was Mimara's, Rumi's, or the stocker's. Mima had many illusions about her inner self and she was almost convinced she was mad and had killed these people herself. Rumi had many about her being Mima and performing with the group.
-At the end you get glimpses of Rumi in the red suit (which is the reality) and glimpses of Mima (Mima's illusions of her inner self).
-At the end the truth is revealed. Rumi is put into a hospital still believing she is Mima. But Mima now knows the truth.

Try watching the movie again keeping these observations in mind and I think it'll be easier to understand and try to come to your own conclusions on what is reality, what is Rumi's illusions, Mima's illusions, etc.

I still believe that we view nearly the whole film through Rumi's eyes, Rumi only using the mental image of Mima to relive her own past. Afterall this is what Rumi does with the doctors in her psychiatric ward, imagining them as the detectives in a TV show. Since nobody knows who she is and nobody has heard of Rumi, it almost seems to me as if she was never really much of a star, and perhaps the meeting with Mima was a brief interlude of sanity in the midst of her MPD. I also see me-mania as a protector of Mima and not a collaborator with Rumi. This movie is just so fun, its great to come up with a whole bunch of theories at the end. Who knows, maybe even the directors don't have a straightforward answer, but thats the point, this film isn't straightforward, it can't be simplified and it definitely doesn't use a literal turn of events to show what happens (Just because we see mima, doesn't mean it is mima etc)