Help me..

So I have a sister, who used to be super close to me. We did everything together, everything. She's now 12, and I'm 14. I made a huge mistake and introduced her to my friends. She then got their numbers and began texting them, blocking me out completely. She no longer wants to do anything besides text. This has been going on for a year and a half, almost 2. She's also been making mean comments to me, which make me feel like a worthless nothing. It's constant. I hide in my room, and I cry. She calls her friends and complains: "Oh, ______ is crying like a freaking titty. It's annoying as Hell. Save me, please." That hurts too. She also talks behind my back and lies, saying I 'left her' when I didn't want to follow her down the road to get her rabbit's nails clipped, or when I don't want to paint her fingernails or clean her room. I hate it, and I'm getting fed up with this. Advice?