My cousin

I'm at my wit's end with her. She's going through a lot right now. She's only 14 and she's in with the wrong people. She trusts me and tells me everything (or so I think...) and she's going through some tough stuff and I just don't know how to help her.
She's done pot and drinks on a regular basis. She got high at school the other day, and then got high again later the same day. She sneaks people into her house and drinks. She's rude to her parents. One of her friends has anger problems and is extremely fucked up and wants her to try ecstasy, so I'm trying to keep her away from her. I'm afraid it's already too late. She skips school, gets bad grades, her mom found pills in her room (which she hasn't told me about yet). She got in a fight with her mom and I brought her to my house so she wouldn't go to this other girl's place and do something stupid. Her mom doesn't trust me anymore; she thinks I'm the one giving her the alcohol.
Yet, this poor girl has it rough at home. Her dad covers for her but plays dumb to her mom, so when she needs him to be honest he doesn't help her. My grandma (who lives with her) also plays dumb. She has so many people enabling her, which is only hurting her more. But her younger twin sisters are spoiled and get rewarded for pleasing their parents, which they've learned they can easily do by ratting out their sister so they've began lying to them to get rewards. They told them that one of her friends showed them pot the other night, which isn't true because I know for a fact that the friend they said did it was at home with her parents that night. My cousin is also constantly being compared to me (because apparently everyone thinks I'm fucking perfect), which is never something anyone needs to hear. She's under a lot of pressure and nobody is helping her. I try by stealing her away sometimes and trying to show her you can have fun without using substances, but then she just goes back to her friends.
I told my mom tonight after a big fight she had. Her mom knows some of what's going on, but not all of it. I told my mom everything I know, but she isn't going to tell my aunt, which pisses me off. I can't because I feel like my cousin trusted me and I'd be betraying her. I know it would be the right thing to do and all, but then she won't feel comfortable coming to me anymore then we'll lose her. I just want my aunt to know that I'm the only one fucking helping her.
I don't know what to do. They're trying to get her counselling but they need to wait for her to say she's ready for it, but she's really stubborn. They're also waiting for her to get referred to an eating disorder clinic because they suspect she's bulimic.
I feel guilty that it pissed me off that she's getting referred. I wanted to shout "She doesn't have a fucking eating disorder! I do! Get me help!" But she does need help, just not with an ED that doesn't exist in her life. I just wish she could get all her shit sorted out. I'm under a lot of pressure because of all this, and it's pushing me farther into my own ED/depression, but nobody knows. I just want to not eat until I'm dead now.
AGG! I just want to run away. I want to do anything to get out of this hell hole I'm stuck in. I'm so stressed from everything going on (work, school, ED, family shit, depression) and I feel like life is just not enjoyable. What is the point? Every day I wake up and I tell myself I'm nothing. All day I believe it. I'm never happy. People think I am. It's all just a deception. A really good fucking deception. I'm such a good liar that nobody thinks there is anything wrong with me, but sometimes I wish they did. It would be nice to be able to live and be happy, but it's been so long that I forget that that exists, that it is still possible for me.
Sometimes I wonder how much of the shit that goes through my head goes through a normal person's head. Do normal people feel guilty about eating food, or even junk in the least? Do normal people ever feel just blah about life? Do they ever wonder what life would be like without them? Do they ever want to just stand on a really high rooftop and scream to the sky?
What exactly does a normal person think?
I have homework to do. Faack. It all seems to trivial now.
I guess...peace out