Is it normal that i always get treated like the "bad guy"?

I posted something like this before, but now iys a little different. Me and my sister fight often, and when we do, my mom teams up with her. I cant remember all the fights, but I know I did put the middle finger right up to my sisters gace and said "I'm gonna shove this up your ass!" And I've already called her stupid (she's in a focus grou). But, she's already said that she enjoyed seeing me suffer tells me I don't have the beauty to do this (she was holdong up a picture of herself) Now, what about my mom? She's called me mean, called me a fucking stupid idiot, asked me what the hell was wrong with me... Now please no mean comments, but please tell me what i could do and who's really the bad one. Oh yeah, i forgot, once, whem I was about 11 and my sister 9-10, she tried to stab me with a steak knife, but the only reason she didnt was hecause my mom walked into the kitchen before she did. Literally, the knife was inches away from my thigh! After we explaned what happened(I can't rmember a thing) I got in trouble, yup I did, because i was th eone who had continued it. WHaT?!?! It's like, no matter what happens, its my fault. And you know, its so hard to bottle up my feelings all the time. Iin?