Why does my sister always snitch on me?

okay im 15 and shes always telling on me shes 22 and lives at home with her 2 yr old son..one day i took her phne with out asking(ikw bad) then we were in the kitchen and she ask me did i have it so i confessed(good right) she was coo for like 2 minutes and then was like" come on(her sons name) lets go tell on your auntie" i was like WTF??!?...so they told and i got fussed then was mad cuz all he said was next time your in trouble then one day i did some really bad i got caught sneaking out our dad was out of town so she rushed back into her room and told on me she didnt even say nothing to me she just called and i got a long speech from my daddy about babies and stuff..so a little before that i siad i wasnt going to talk to her anymore so i didnt went a long time..so my sister get an EBT card so we let her buy grocereys and she told my dad why should i eat her food if im not talkin to her?...so my dad bought me some food and made me talk to her everytime we get in an arguement she brings up all the wrong i've done calls me a bad person and say i have no friends once she called me a whore..wen she was in high school i never told on her even ttho i had a ton of dirt and water to spill i kept qiet from the Alcohol to boys in the house while my dad was at work and one time i caught a guy comming out the window early in the morning..i never said a word she tells about the smallest things even if i didnt clean up the kitchen due to forgetfulness sje always tell im so confused???