I got beaten up by someone that I know.
Did you do anything to protect yourself?
I went to the police, but they did nothing.
You did not get any kind of protection order? You should see if there is another agency that can get you some support so that you can feel safe again.
I know you are trying to help, but I can protect myself.
You obviously cannot protect yourself from this person without help. If the police couldn't help you then you need to contact an attorney who can advocate in your best interest to protect yourself from this person.