I don't usually condone dishonesty, but in a matter of your safety...do you think you could perhaps skirt the details, or at the very least, convey the message that his guy is a threat without giving exact details? The details may prove extraneous...you could say this guy was an associate (not a lie) of yours who became too attached (not a lie) and you, not wanting what he wanted, distanced yourself (not a lie). He is now invading your personal space (sure as hell not a lie) and you feel threatened (not a lie). I don't know your parents well enough to know if that would suffice (and again, I don't like suggesting dishonesty...), but they'd be powerful assets to have on your side during this.