My best friend copies (idolizes????) me? *SUUUPER LONG*

I have this best friend, and she's been my best friend for years.

However, in 9th grade I noticed that she was copying lots of things I do. They were small things. For example, in 8th grade I wore t-shirts and jeans everyday and so did she. In 9th grade I decided to wear nicer clothes and a bit of makeup and so did she. Also, so was trying to get me to read The Infernal Devices, and before I read it she told me how much she HATED Jem and why I would too. However, when I read it and told her I liked Jem more, she said "Oh. Yeah. Jem I really like him, too". This bothered me excuse I KNEW she lied! Lots of tiny things like this continued to happen. . I decided that this was normal for best friends- and also, isn't mimicking the high form of flatter? So, I told her subliminally that I liked it when she was her own person and didn't always copy me. This worked for a while.

However, 10th grade rolls around. She starts to pick up on it again- except this time it's ALL areas of our lives. I started watching hockey, so did she. I wanted to eat meat again (we became vegetarians together), so did she. I liked a guy, so did she. Lots of them were weird and unnerving like those two: they're supposed to be personal choices yet she did the same thing as me right after I did. It was also weir things that shouldn't matter. For example, I got the whopping cough in September of 2013 for 2-3 months. It was, of course, extremely painful and miserable, but I'm a positive person so I told everyone that "Hey, well my upper abs are really toned because of all te coughing"! One day I was telling this to the swim team, and OF COURSE, my best friend said, "Haha, oh yeah, that's been happening to me to!" First of all, she has a cold. She had a stuffy nose and headaches for three days. She was hardly ever coughing, and even if she was, three days isn't enough to get toned upper abs! Also, me and my friend (calling her f1 for now & future purposes), look A LOT ALIKE. So much so that these two guys on cross country asked if we were twins! Well, on swim team, people would tell me and f1 that we looked a lot alike, and my best friend would barge in and say "yeah, everyone tells us that US THREE could be twins"! No one ever said that, an we don't look alike at all! Again, this was EXTREMELY ANNOYING, but manageable. I tried to give her a subliminal message, but it didn't work this time. The worst part of it that was people would comment on how alike we are, and she would seem extremely proud. This bothered me because I wanted people to recognize me as my own person, not some copy of my friend. Anyways, this dilemma was heightened.
It all gets worse when you add my two other friends to the picture (f1 and someone else- we'll call her f2). F1 starts to get mad at my BFF because she is a know-it-all. It's true- she refuses to be wrong! For example, one time at lunch this week, my and f1 we're talking about college applications and how they're near the end of junior year. My best friend thought that was wrong, so got in a HUGE argument over it with us. She even "looked it up" (she really didn't- I think she knew she was wrong but didn't want to face it). It's not that fight that bothers me-it's the fact that it happens continuously over dumb things that don't even matter, like when we apply for college. Also, with f2, my bestfriend is mad at her and we have no idea why. It was her birthday this last weekend, and my best friend invited me (just me) to the mountains with her. Also she completely ignores this girl during class and never texts her back.
The most strange thing, though, is that my best friend never talks about this to me. She's my BEST FRIEND, she should be telling me everything!!!!! Instead, she acts like she's all dandy with f2 and like nothing's wrong. Also (again with the subliminal messages), when I told her I "hate when people won't admit they're wrong" she agreed. And she didn't even change anything after that. When I talk about these two other girls, she just acts like everything is okay when it isn't.
F1 and I have talked about this a lot. We believe she hates being wrong just because it's a part of her personality and that she has sort of a superiority complex. But we think it would be beneficial to her- especially when we grow up- to know that she does this. How can we tell her without being rude? We have no idea why she would be mad at f2, except for f2's success (in swimming, student government- which would make sense for the same reason as the above question), but we think that's mostly between them and don't want to interfere in places we shouldn't be. Lastly, f1 thinks that my best friend idolizes me and my family. F1 thinks that she wants have my life, especially because of my family (I'm not exactly sure if this is true, because I've had troubles with my mom in the past and have shared it will my best friend- but the idolizes me part makes sense). This would explain why she copies me and won't tell me about her problems. I jut want her to know that I don't care of we like different things or if her life is different than mine, and that I don't want to be a friend with myself, that I want to be a friend with HER. I just don't know how to tell her that. If you could help me that would mean so much. Also, f1 and f2 want to confront her about their problems with her but we don't want to do it all at once. Also, we think that (based off her personality) she won't take it so well and maybe try and blame it on us or say that she doesn't do any of this stuff, which won't help at all. How can I tell her about this without getting the above reaction, and how do all three of us confront her in a way that won't overwhelm her? Although it may seem like I hate her because of this, she IS my best friend and I really do love and care for her, all three of us do. That's why I need so help, especially because I do not want to lose her. Thanks so much for reading this and possibly trying to help. It means a lot.