Am I overreacting to this?

My friends has done some stuff to me in the past that I've forgiven her for but lately she has gone quite out of hand like throwing a ball at my head am then laughing with people about it. So i told her that i didnt want to be friends anymore. she accepted it but keeps trying to wriggle back in. i am getting a little annoyed with that. should i tell her to leave me alone or just leave her to try and try?