I'm sorry all that happened to you. I was placed in a 72 hour psychiatric hold once and I can't even imagine having to stay in that environment for as long as you did, but I have had to live in multiple environments that were traumatizing to me in various ways throughout the years. Something I've come to realize is that people who aren't highly sensitive to their environment are simply never going to understand how bad things can make me feel. I might be feeling like my brain is on fire 24/7, but that doesn't mean that anyone around me fully realizes that and they're just ignoring it or something. I've had to learn to stop seeing people as neglectful or even malicious just because they experience the world differently than I do, and therefor don't understand (or possibly even recognize) the extent of my pain.

I was recently diagnosed with PTSD, so personally I've been trying to work on myself from that angle. I would recommend reading about that, and maybe discussing it in therapy if you can. (I'm not saying you or anyone should be self-diagnosing anything, but just that there are possibly helpful aspects of reading about such things, even if you don't necessarily have that exact thing.)

So far in my day to day life I've just tried to remind myself that I don't need anyone else to validate or approve of my feelings and judge whether or not I was "legitimately" traumatized by something. I've tried to remind myself that the situations are over, and urge myself to feel relieved about that rather than angry or hurt that they ever happened at all. I've tried to tell myself that if I do urge myself to move on from the situations, it doesn't necessarily mean that I am approving of anything that happened or forgiving anyone who doesn't deserve to be forgiven. I think it is okay to work on simply moving past things for your own mental health, even if they haven't been fully resolved (although obviously that is much easier said than done) because some things in life simply can't be resolved.

I understand wanting to feel like someone is on your side, though. One of the worst things about being extra sensitive to everything is how isolating it can feel. One of the worst possible things that can happen to people like us is not having any control over our environment, and so few people understand that. I hope you'll never have to live in a situation like that again. Unfortunately even in mental healthcare there seems to be little understanding of the fact that some of us need to be handled differently and that the things that have been helpful to others can actually be harmful to us- but we must try to remember that most people do mean well, even in crappy understaffed/underfunded mental health facilities.