Maybe it came from the girl in your dream. Your dream was meant to warn you of the horrors that were to come.
Whatever the case, I suggest that you barricade your dwelling, arm yourself, and sleep with one eye open (it kinda hurts, but it's worth it). You've got a grade-A psycho here. Or just a grade-A jerk.

On the subject of dreams, I once had a dream that I was riding a pterodactyl through large hallways. I've also had dreams that accurately predict certain things happening the next day, dreams about disappearing and reappearing cats, dreams about girls on the bus that don't want to talk to me, and dreams about myself being mauled by large dogs. Fun stuff.