Why does my mom not like me plz read whole thing?

all she does is watch tv be mean to me and play with my brother and sister they are both 10 and im 13 seriously she is so mean to me telling me i look like a horse making fun of me every chance she gets spending more money on my brother and sister whenever i try to tell her she treats my brother and sister better than me she just rolls her eyes and tells me to shut up this one time my little brother attacked me trying to beat me up and then he went to go get a knife from the kitchen yelling IM SICK OF YOU so i ran and hid in the bathroom with the door locked and he yelled DID THE LITTLE SCAR DY BABY GO AND HIDE and then when my mom came home and i told her she said it was my fault because im the oldest i was crying and everything and then she just laughed and said are you actually crying I HATE MY BROTHER dont tell me she loves all of you equally because she doesn't she tells me im bad for no reason all the time she has never hit me but her yelling scares me