I hate my cousin so much?!?!?

Ok. Well im 12 and she's 8. She thinks she can do whatever she wants! Like for example, today i was swimming and she just showed up and got in my pool with out asking! I told her " What are you doing?" and she said, "swimming duh." and she acted like it was her house! And then she also just comes to my house to drink my soda since her mom doesnt let her drink soda. And she just opens mu fridge without permission! My mom is annoyed about this but she doesnt do anything because me cousin is a big snitch and tells her parents everything! She's from my dad's side but my gramdma from my mom's side takes care of her while her parent are at work. And she doesnt treat my grandpa with respect! Like if my grandpa say Hi she just rolls her eyes. But if she see's that my granpa has money she hugs him so he could give her money. She also rubs everything in my face! Since my family isnt very rich she always tells us about everything she has! Like i havent beem to Disneyland and she tells me " you guys suck. You never go to disneyland. Ive been their a 100 times not like you" and well we dont have those refridgerators that make ice but she does and she told me "you guys are so poor. Yoy cant even afford ice!" bcuz we get those ice cube things and put them in our freezer. And well i could go on about how she calls us poor but i wont. And im really irrated already and i just want help!(: