I got saddled with a diagnosis of BPD and PTSD back when I was 15. Before people flip out a lot and scream to high heaven that ONLY 18+ EVER for personality disorder diagnoses and that is by and large the rule. My case was severe enough to warrant it. Anyway, shelve that.
Very early childhood trauma left me pretty fucked from the start. Lost my younger sister (she was a bit over a year) at the age of 3 1/2 due to what was frankly a freak accident. Taking a bath, Mom looks away for an instant, she somehow fell and hit her head before going underwater. I pulled her out but the damage was done. Got flown to the hospital and put on life support. Brain dead, would have been a vegetable if the plug hadn't been pulled. Parents said that my personality totally broke and the me I was before the accident died with her - maybe it's better that I don't remember how I was before then? I mull it over a lot.
There was a lot of things that happened to me later in life that probably contributed too. Near death experiences, more notable ones being some deranged high schoolers trying to kill me (or at the very least severely injure me) when I was in fifth grade and, ironically enough, almost drowning. Nearly saw my dad die in a motorcycle accident. Then you got the whole bullying thing throughout all of school, which only served to compound my existing issues. If I hadn't gotten assfucked by life straight out of the gates it probably would have been easier to tolerate.
Coming up on two decades later I still struggle to shake the idea that it's my fault she's dead. The nightmares play their hand in that, showing me shoving her, hitting her, or holding her under - things that are patently false. My parents still need to remind me that it wasn't because of me sometimes. Thanks to therapy I am a lot less prone to freaking out over baths, and I can handle the nightmares better. I honestly doubt I will ever really be fully healed from all of this, none of my family will. Still, it's mostly a matter of time now. Time and pressing on.
I don't know how helpful I would be in terms of being someone to talk to for others, but all the same my inbox is always open too.