What the heck is up with this punishment?

Ok, my sister and I fought, dad got mad, and I got sent to our room. the reason for the fight? She started scratching me, then I told her to stop. She mimicked me, then scratched harder. So now I'm in my room, wondering why even though she started the fight, I'm the one treated like the bad sister. I have scars from where she's actually punctured my skin, including one from four years ago, like smack dab in between the veins in my wrist. By the way, she likes to say when we fight that I'm unfair because I'm hitting her while she's using her claw-like nails to hurt me. (I don't have sharp nails, or really nails, because I had a habit of biting my nails until a week or so ago.) She also has no sense of humor, and if you say anything bad about her, she gets super mad, yet she can say anything in the world about you. So, why, when she's always the one to make things physical like this and make things flair into a fight, is she getting treated like the victim here, being aloud to continue watching videos and talking and hanging out with our other sister, while I'm up in our room alone!?