What would you actually do if I broke down sobbing in your office?
If you seemed unaffected and just used your empathetic therapist voice I'd be mortified and deeply ashamed

I don't know if you actually care enough to feel upset by the stuff I tell you. I know you've heard a lot worse. But if you're feeling something could you please let it show?
I know there are a million reasons I've told you that I need you to not react emotionally. But I do trust you to be responsible for handling your own emotions by this point.

Emotion from you would make it feel less embarrassing. It would make me feel like I was allowed to be emotional.
You bring up how I'd react to someone else describing having had these experiences. If you're feeling anything like how you've pointed out I would feel, please just let it show. Not all the time, but once.
It would help me feel like I'm allowed to let it matter.

(this is one of the things I will never actually tell you. Because there's a chance you're not controlling your own emotional reaction for my benefit, you just don't feel that strongly about it/me. And I don't think I could handle you telling me that, no matter how kind you tried to be about it)