I don't think there is anything wrong with you.
Maybe watching it and reading about it over and over is your way of taking something horrible and making it "normal," or less significant. Like if you can expose yourself to it enough then it eventually won't bother you anymore. I think this is a very normal response.
However, it sounds like your "obsession" with it is really bothering you, and that it is not helping you to feel any better. Maybe you can work with your therapist to discover some other, healthier coping mechanisms that you can replace watching the rape scenes with.
I hope you will feel better soon. Thanks for sharing this.