How can I 'unsee' this and stop being paranoid?

Tell yourself that it's only a movie, NOT reality. Somebody wrote that script. It was in another person's imaginary, twisted mind, not yours. Repeat, 'it's only fiction' several times, and believe it, Now, get on with your extraordinary, productive life. Remember, you're a grown-up! You are in control of yourself. This, too, will pass. Good luck!