I need to separate from her and I feel like I have no roots of my own to stand on for it to be safe for me to acknowledge the truth.
This is such a good point Bloopsy. I think whether it is an N parent or N romantic partner, one big part (of several) of why it can be so hard to let go of the unhealthy relationship, is that we can feel like we are not strong enough on our own, or don't even really have an identity of our own.
We can feel so fearful, alone and lost on our own, and this can keep us clinging to relationships we need to let go of, or keep us getting involved with similar unhealthy ones over & over.
I clung to a romantic relationship with someone with N traits 3 years longer (relationship was total of 5) than I knew 100% that I should walk away, because I was so afraid of the fear, aloneness, and lack of clear self identity I felt. So, I just kept the magical thinking going, rationalized and remained in denial for 3 years.
It is really hard\scary to face the fears within oneself, and I realize I was using the relationship as a distraction in looking at my own self and facing inner fears. As miserable as I was in the relationship in the last years, it was still serving as an emotional "crutch" for me. It felt safer emotionally for me to be where I was, than to turn to a place (i.e. leaving) where I felt there was just about zero foundation, just like you say.
I also was convinced I loved this person more than life itself which didn't help

, but these things are complex, and there was more to it in relation to the other things I am writing about.
But I even think that my loving this person so deeply in spite of all of the pain he caused me, may have been related to my lack of a strong or even really existent self identity/foundation, and some of my other inner fears unrelated to that person.
Growth
is painful as they say, but at least it is a fleeting pain with the potential for wonderful rewards. The pain of remaining emotionally attached to an N is a never ending life sentence, with no rewards or happiness to hope for.
I remember that as I think about new relationships, and as I still battle fears and work on my inner self.
BT