I hate someone in my school who I think likes me
Why do you think they like you and why hate them?
I hate a person in my school because I think they dislike me when in reality they love me
Why does them liking you make you hate them?  It is rude to treat others with disrespect.
I am aggressive and love to fucking hurt people.
You should look into releasing your aggression in another manner that isn't harmful and disrespectful to others. They haven't done anything worth your aggression. Maybe you need a physical activity or sport to channel that agression into?