Dealing with my arrogant cousin! HELP D:?

Okay.. well, my cousin Kelly is like 11 I think. And I'm 12.. She's so bratty and stuck up, she has TWENTY THREE pairs of shoe, yes 23. I'm not joking we counted. I have like 4. She is SO spoiled. She's an only child and my dad's always like ,when I complain about her bragging , shes an only child. blah blah blah. She brags so much, she has all of these clothes that don't fit and she doesn't even give them away to anyone. Like homeless ppl or good will. I always do. shes like 3 sizes bigger than me. Anyways I'm pretty sure I have to see her soon. The one thing I have that I love and it's actually pretty nice. (I payed for it myself :D) is my phone. she tattles when i'm on it. and my aunts like lily get off your phone go play with kelly. I mean i just want like 5 mins on my phone geeze. and she tattles for everything i do...so what do i do when she comes? I obviously cant ignore her.. thanks x