Yep, sharing your trauma should be an exercise in trust and intimacy. People should not share their trauma with others just to provoke a specific emotional reaction. I also have some second-hand experience with what you mention. One of my SO's parents is a hideously narcissistic person who would trauma dump all over my SO to invalidate any feelings or concerns my SO might have. That, combined with gaslighting and other forms of emotional abuse and neglect, plus some physical and sexual abuse set my SO up with a fuckton of trauma to process. They also had a hard time with hearing of other people's traumas, although for them it was in more specific circumstances, rather than generally.

I like to think that most people trauma dumping are victims who aren't creating another iteration of the victim/abuser cycle (I base that off of nothing but my own hopes, I have no numbers), but there are definitely people who have weaponized it. I'm sorry to hear that you went through that :/ hopefully you're free from those toxic people. After my SO's parent kicked my SO out (a horrible night, but one of the best nights of their life in retrospect), my SO moved in with me, did a whole lot of EMDR therapy, and has managed to heal from the damage caused by their parent. Hopefully you can find a treatment, process, or mindstate to help you, since it sounds like you still have some wounds from what was done to you.