I think I might have something similar, not so much disturbing images, but I imagine horrible scenarios quite often. Like for example, if I'm crossing a bridge, I will often imagine the bridge collapsing and me falling to my death. Or when I was living in the city, if I passed men on the street I imagined them attacking and murdering me. All sorts of different scenarios, all that end badly for me. You've gotten some really good advice from Wendy and Veiled, I'm not sure what else to add except that I think I can relate.