Main thing I wanted to point out (and did so rather clumsily, I admit!) is that she can't really have it both ways. If he truly frightens her, and he really is a dangerous person, then she should involve the authorities. If he's just some jerk, then block him and ignore him and be done with him.
I'm also mindful of the fact (which I'm sure most people are, too) that a lot of people who come here don't write English too terribly well and so may mean one thing when the reality is something rather different.
Hence she really had two choices - to either seek protection from the authorities from someone dangerous (and admit he was), or to drop that idea and get it through her head that a revenge plot against some jerk is just plain stupid.
I'm about 95% sure it's the latter. But just in case it's the former (plus people often Google these questions years later and don't necessarily have identical problems), then that would be the remedy.