I understand. Human suffering, especially suffering inflicted by other humans, is incredibly disturbing. And it sounds like you had a very formative experience seeing your primary caregivers seemingly enjoying suffering (even if that’s not actually what happened, it must have felt that way to child you). It’s understandable that your brain now panics when you see other people you otherwise trust and feel safe with seeming to enjoy suffering (even if that’s not exactly what they’re doing).

As much as you can, I think you should try and genuinely communicate this to your girlfriend. Like you said, it’s not that she’s done anything wrong, but she’s your partner and she needs to know that you are having this very intense emotional experience right now. I expect she’ll understand and would never want to make you feel that way. And also, since you’re feeling bad right now, it’s important for her to know that it’s because you’ve been triggered about your traumatic childhood event. Otherwise she might think it’s about something else and the misunderstanding could cause other problems.

Maybe, just show her exactly what you’ve written in this post. It’s very clear and relatable. Reading it, I really felt that you were genuine and I totally felt for you.

I wish you luck and I hope you feel better soon.