I have a nosy ANNOYING cousin my age HELP D:<?

Alright well my names Lily and my cousins name is Rachel. We've always been like best friends when were together in REAL life. But on facebook she's SUPER nosy and rude and gets jealous over EVERYTHING. she live 3 hours away.. and she got mad that I hung out with my BEST friend. She's crazy!!! I mean geeze. I can't hang out with her..she lives 3 hours away! I got highlights and she's like eww your gonna ruin your hair! So i stood up to her and said ' I'm not going to let you ruin my day , Bye ' because it was my special day for reading ten LONG books since summer started. Then SHE deleted me. Wich i was pretty happy because then I couldn't get in trouble. anyways he messeged me like why do u hate me I'm just like bye and you cause drama but i dont hate you. then I claimed I had to go to sleep. How do I explain to her that I JUST want to be friends in real life not on facebook.. basically who can write like a paragraph for me to message her. It's annoying having her as a friend on facebook because she comments on EVERYTHING and it's mean , she's also nosy and jealous I guess...and I have anxiety and stress isn't healthy for me. She's my cousin I have to put up with her and she threatens to tell my mom. It's pretty childish. I'm sick of her. What do I tell her? She keeps sending me friend request.. she' my #1 stalker on FB :3 Thank you everyone. - Lily x (I'm 12 turning 13 if it helps)