Me and my sister always get into fights that she starts, like today at the store, she wanted to help me and I said no, so she started to get all mad, and started a fight, which got me grounded from everything I like for 2 months (FOR SOMETHING STUPID).

I now want to punch her, but my mom said to get over it (nope I can't). My sis is acting like she just won a bunch of money against me (while I am sobbing in bed).

What do I do >:(

no therapy, I was grounded from my phone, I am doing this on my work computer.

so, why did you tell her no?

You have something against having her help you?
Did you snap at her when you said no?
It takes two to fight.