I would suggest that someone who would call the cops on you or your friend is not worthy of your friendship.
I would steer far clear of them. By that I would make it very clear, don't call, text, email what not to them both.
And if they persisted in contacting me after, well then I'd call the cops on them for harassment. I get the sense that you are very young though, so I will also suggest you get parental advice/involvement going on too.