Accidentally while i was brushing my teeth i hit tonsils/ the back of the throat is this bad?

No, not at all.

The trauma to your tonsils is minimal so no damage has occurred. Maybe a slight irritation so gargle with warm water and honey, also rinse with an antimicrobial mouthwash or eat ice -cream, all will sooth the area if you have any pain.

You bruised yourself. It will heal. Just as if you banged your thumb with a hammer it would heal. Please remember that a toothbrush is designed to gently wipe bacteria off of your teeth. Use it judiciously.