I'm going to bust my little brothers lip
Why would you bust your little brother's lip?
I don't like my little brother.
It is wrong to be violent with your brother. It doesn't sound like he did anything to you so you shouldn't hit him.
I don't like him, and I want him to know what it's like to have someone hurt him. That's all.
Not liking him is one thing but that doesn't justify wanting to hurt him. You should try not to be mean to him as it'll affect not only how he sees you but how he treats you in the future. You don't have to like him, but you should at least try to tolerate him.