I'm going to call my sister a selfish brat
Why do you think your sister is selfish? What happened between the two of you?
She hits me  and she always insults me even if  I'm right.
You have every right to get angry at your sister for insulting you. Calling her name names would escalate the situation. You better distance yourself from her.
I don't want to distance myself from her. She deserves everything she gets from me.
I can see why you would be upset about your sister's behavior towards you. But calling her names is not going to fix the problem. It would be better to either ignore the problem or try to get along better with her.