What do you think about me wanting to cause massive trauma to a girl that I know?
Why do you want to hurt a girl in that way?
I have seen her constantly mocking me for being so fat
It's wrong to want to hurt people, in any way, for any reason.  Even if she is being disrespectful to you, you should have enough restraint to not want to seriously injure her.
We will see. I want to hear her cry and ask me why
I'm sorry that you were hurt by her words. However, this is a situation that requires you to be assertive, not aggressive. Wanting to hurt her is wrong and if you don't show restraint, you will end up hurting yourself by getting arrested.