I think my girl has come to terms with it in many ways, she is pretty stable, especially in how she externalizes stuff... like we've never been in a fight even once, because we both don't do anything bad to each other and neither of us lashes out when we feel our insecurities flare up, because we realize that's our own shit. Hers stems from her dad being really overbearing and intense (yelling, controlling, etc, I think he hit them a few times too, she mentioned it once though not sure) when she was young, plus a really intense divorce of her parents and then her mom basically just running away to Hawaii, leaving them all and never coming back (she visits her mom sometimes and they're pretty close but that's gotta be intense, to have your mom just run away when you're like 9 years old). She is extremely quiet (like the volume of her voice, it's hard to hear her sometimes even, in the car I have to turn the music off or there is no chance I can understand what she's saying) and her main issue is, she feels like she doesn't know what she wants from life and doesn't know how to be assertive to get it. Loud noises make her shut down too, if someone is yelling or excessively angry she will get extremely uncomfortable. I honestly wouldn't have thought she had PTSD but she says the symptoms fit her internal reality perfectly. I think she struggles a lot but she is great at not externalizing it or putting it on others, which I really admire about her. I think her dad putting his shit on her/her siblings made her vow to never put her shit on other people. She has periods of time (generally related to her menstrual cycle) where she is really happy and periods where she is depressed to the point of crying, saying she feels out of place in the world, useless, etc. I think she always is a little depressed deep down. part of it that her dad paid for her to go to college but for some reason he decided he would only do it if she got an art history degree. She didn't want to get one but she wanted to go to college, so she went. She had a super stressful time in college because of it, she wanted to study biology and work with conservation or something with nature like that. But she feels like she can't now, she is unwilling to go back to school because she said it drained her so much last time she couldn't handle doing it again, and she has no interest in doing anything with her art history degree (talk about a strange field of study to force your daughter to do...). So she's kinda stuck in this limbo of having throwaway part-time jobs, trimming buds for 2 months a year to make a big chunk of money, and not really knowing what to do with her time besides that.
I will say when she took mushrooms with me she got pretty down for a day or so afterwards and she told me it always happens with mushrooms. But she did have a good MDMA experience which she told me helped her to open up in a permanent way, but it was not a full experience and she wants to do it again and go farther.
Not sure exactly how to help you out, sounds like maybe a bit of a different situation, I don't know. I think my girlfriend's PTSD stuff manifests as shyness, inability to assert herself if at all intimidated, and difficulty getting close to people besides a select few, and a lack of confidence in her own abilities/worth. I just try to build her up and make her feel good about herself, and always be there to talk if she wants to. I never try to get her to talk about it if she's not trying to.