It took a long time for me, and I'm a healthcare professional who knew, intellectually, what had gone on. I still to this day mourn that loss of the "normal" delivery, and pay a physical price (lymphedema of my legs and other things) thanks to our experience fifteen-plus years ago.
I do think that the magnesium really exacerbates this feeling of disorientation, making everything so much MORE nightmarish than it might otherwise be. I was on mag for five-six days, and by the end, was talking to people who weren't there, seeing things on the walls (giant cockroaches, YUCK!), etc. It does weird stuff to your brain, and the cerebral edema doesn't help either.
My daughter's fourteenth birthday was the first birthday where I wasn't remembering everything that had gone on and finding those feelings all welling up again. Interesting thing is that she is obsessed with her birthday -- in a good, fun way! She notices when she sees those numbers come up on the clock, and absolutely LOVES the whole birthday thing. So I have tried very very hard not to pass on my trauma and tears to her around the circumstances of her birth. She is aware of it; she spent two months in NICU, had two surgeries for NEC (even though she was 37 weeks, she did not get enough oxygen during delivery and was born depressed, blue, and with scarily low oxygen levels which didn't improve for some time. However, she is an honor student and we were very, very lucky, all told. Just living everyday life and seeing your child grow and develop in spite of that horrendous beginning helps a lot, I think. And also knowing that a lot of the scary things have simpler explanations -- like the monitor leads going off every few minutes, probably really just being caused by a loose electrode rather than anything in your heart since it happened when you moved -- helps a lot. The magnesium does very weird stuff to your brain, and I know that a lot of the frightening things that happened to us had their nightmarish aspects really magnified by the drug. Yes, it saved my life, but sure left me with some VERY weird memories!
I know that cognitive therapy has worked very well for a number of people who are suffering from PTSD for a variety of reasons, so it might well be worth looking into it for you. Also, it's easy for me to say that "it takes time" because I'm looking at it from the perspective of a parent of a high-schooler and we've had that time.
I hope you're able to find healing in whatever way works for you, and sooner than I did.
Mom to Rebecca, now 16 and honor student. 37-week, two months in NICU for her thanks to NEC and meningitis. One month in hospital for me, HELLP syndrome and severe hyper-reflexia. All healthy now, more or less!