Why is a 7th grader obsessed with me?

What is the freaking deal with this kid? I’m a sophomore and this chick is absolutely obsessed with me! I’m the worst role model in the world no lie and she’s like in love with me! It’s really ridiculous. It all started in august last year, she was at my friends house because of her little sister. And she texted me so I replied. BIGGEST MISTAKE EVER. Ever sense she’s followed me around like a little puppy dog. How do I tell her to leave me alone without making her end her life? That’s what she told me. And I quote “there’s no point in living without you Haley. You fix everything and make me happy” Wtf? How the hell do I do that? Yeah sure I chill with her every now and then to get away from my dad but gosh dand cayla!

 I really need some space now. I'm trying to grow up and I just can't with her constantly dragging me back down. I got kicked out of my house and stuff because I went to her house without telling my dad and he accused me of going somewhere else and she didnt back me up. It was bull. And now she just ughhh!!! 
I thought it was cute at first. Like the first month I was all aweee I got a lil sis! now I'm just like go away please? Help?!?!?! How do I make her back off? I even got texting taken away and now she calls me everyday about 3-10 times a day. most of the time just to say hi. Please help me. I NEED her to go away but no matter what I say she keeps coming back! Help me? Thanks sooo much...