my sis took my favorite blanket

so i have this old worn out teddy bear that i used to sleep with every night when i was a kid and i had this red plaid blanket that my grandma gave me, its super old but i still love it, i just can't sleep without it honestly. so today we were home from school cuz of a snowstorm and my little sis is being annoying as usual and i have a big test tomorrow so i told her to go play in the other room or something and she's all like no i want to stay with you and its been driving me nuts. so at night time we were both ready for bed and there was this one pillow that she had taken earlier in the day from my room, i asked if i could have it back but she just wouldn't give it up, she's always taking stuff without asking, so i told her to leave me alone for a bit. then when we were both getting ready for bed tonight, i went into the living room and saw this blanket laying on the couch that looked like mine. so i went over there, picked it up, but then as soon as i did she said it was hers, she's been lying about stuff too much lately. i told her to stop, but she wouldn't listen, so i had a fit cuz its my favorite thing and now i'm stressed out for my test tomorrow. its not fair, why can't she just leave me alone sometimes? i wish i could have my space back.