What can I do now? My friend is being a jerk but I can't stop being her friend. Read on.?

Ok...i have this friend who we'll call Miranda. There's a lot of things that have been happening with her and me lately. Like, one day...I was having a bad day (this happened in the morning) and she came over to me and just started talking about stuff that happened to her and blah blah blah. I tried to act like I cared...but it was kind of hard, considering that I was upset. We went up to a group of our friends and right off the bat...one of the people in the group asked me what was wrong. Miranda still didn't say anything about it and just kept talking about herself. It was like that pretty much all day...she just didn't get that i was having a bad day...which just made it worse, because i felt like I have always been there for her but she was never there for me. Another thing is, she lies to me constantly. Not just to me, but to pretty much everybody. She has told me one thing, but then tells somebody else something else. It's really frustrating and I can't trust the things she says. Plus, I can't even trust her with my secrets. She likes spreading things and telling things about other people...I don't ever tell her like anything anymore. And recently, she was talking to my friend, Hailey and she was telling her that I never tell her anything. She said that she tells me 98% of her life, and I tell her like 3%. Which is somewhat true, because i DON'T tell her about my life because 1)she wouldn't understand 2) she doesn't care 3) i don't trust her and 4) because i DON'T WANT to tell her. But she DOESN'T tell me 98% of her life...maybe of her fantasy life, but not of her real life. Another thing that has really gotten on my nerves and other people's nerves is the fact that she thinks EVERY guy is in love with her! If a guy turns around, she thinks they are looking at her and love her. It's soooooooooooooooooooooo annoying and she's always got some story with a guy in it that isn't even true. It's really stupid and so annoying and i just wish she'd stop. She is so self-absorbed and loves being center-of-attention. Like, I'll be telling a story to some of our friends...and then SHE CUTS ME OFF AND STARTS TALKING ABOUT HERSELF! I hate it. Something that happened just recently too, is she keeps spreading rumors about me and making fun of me and this guy who is my friend...and she keeps taking things WAY too far. She doesn't get it and she just keeps doing worse and worse things. Apparently, she did something that I have no idea about, but I keep hearing from my friends that it's awful and that when i find out i'm going to be crying and might feel like my life is ruined and it involves that friend that's a guy that i just mentioned. I mean....WHAT KIND OF FRIEND DOES THAT?!?! And, I realized that she doesn't really care about anything I say anyways. I will talk to her...and just her, and she's not even listening. I always have get her attention again and again and i'm tired of it. I understand if that happens every once in awhile...but it happens every time i talk with her now. She's hardly ever listening what i have to say. I know friends aren't supposed to be like this..and the thing is...she's like this only with me. Some of the things like the lying, and the guys, and talking about herself a lot, and telling secrets she does with everybody...but she does ALL of this stuff ONLY TO ME! I don't get it...and i'm tired of it. I know I should just stop being her friend...I mean that's simple but...Miranda and I are still friends only because our families are friends with each other..and she and i live on the same street and go to the same church, and go to the same school. There really is no way to just avoid her. And my mom HATES it when she and i get into fights with each other and always makes ME go over and apologize to her. She has never apologized to me first...i always have to do it...which I find unfair. So, I kind of HAVE to be her friend...I really don't want to be her friend. And another thing is, she gets mood swings and can be super sensitive of things you say to her. And if you EVER get in a fight with her, she gets people to follow her and stay on her side, and then you feel like you are so hated because of things people say. It really sucks...and i hate how easy people will listen to her and just go against me. I just don't know what to do anymore...and next year she and i will be going to 10th grade and I want next year to be a lot better. So, if you could please help cuz i am really stuck and lost and i don't know what to do. Thank you in advance.