For me personally - I had a long stay in a MH unit in my late teens so accessed therapy (of a sort!) and meds then. I didn’t have much family contact for a long time ( have more now) and was lucky to find myself a fulfilling career and make lifelong friends in my twenties that grounded me and helped me through subsequent crisis’, of which there were many! And then as I matured, I had therapy, did a lot of my own reading and research, meds on and off, exercise, worked and so on. So not one thing, and it is still not straightforward.
i don’t think it will be for my children either and as I said, they are ND and I think I am too. But we have a stable, loving family home and I’ll make damn sure that they are supported and nurtured in the way we weren’t, however hard.
My siblings have had different journeys and again by no means straightforward. But they function and contribute to society, they are good people. We are not close really though- suspect we are all triggered to an extent by seeing one another, although we do love each other.
Life is complicated.
I do really feel for the OP, it does sound very difficult and I understand that she needs to protect herself and her DD. I suppose I struggled a bit with how cold she appeared and the lack of expressed empathy for her SD, who is still a child. I guess that this is a coping strategy though.