You need to do the visual equivalent of this:
Nope, you didn't see him. And if he talks to you, nope you didn't hear a thing. If he insists, tell him ONCE: "I'm done talking to you. Leave me alone".
As we say in French, "POINT FINAL, C'EST TOUT!" (i.e. that's it, that's all).
No contact will be your saving grace.