Something like that is very common with OCD and I've had similar thoughts myself. I do "obsession time" where I do nothing but think about what's freaking me out for ten minutes at a time to try to become desensitized to my thoughts. It's......horrendously awful, to be honest, but if you make it through a few of those you may start becoming more at peace with your head. I was terrified to stop and really think about my thoughts because I was scared that I supported it/that it aroused me/that I was a bad person, but remember you are here because this causes you so much distress and that stuff like this is all about what OCD is and how it works.

Also, the only real way of combating obsessions/images in my experience was to think about them (dive into the deep end, so to speak) which is completely terrifying and awful, no getting around that, but remember (1.) Your thoughts don't make things happen, (2.) This is what OCD does, and (3.) If you were a bad person you wouldn't be in so much distress over it.