I was wondering does this also happen to you with media images by any chance? That's a trigger for it for me, but imagination alone is powerful too. I think the brain just forms these pathways that default to something horrible happening, and all the vivid images, sounds, etc. that go with it which I'm sure become more acute after PTSD, like having a "flash-forward," even if the thing is unlikely or impossible. But yeah, I def think your experience is related to it, and you're not crazy. I know rationalizing doesn't always help, but maybe you can make a mental list of all the reasons why those things will not happen, and then find something like OneDay89 said that requires full brain power to get your mind off the graphic stuff.