Your story resonates with me, Been There. Like you, I put my father on a pedestal because he was the parent who didn't terrify the crap out of me with out-of-control rages, he never battered me, never even touched me in anger, and he never destroyed my soul, my self-esteem with verbally/emotionally vitriolic abuse like my bpd mother did.

But on the other hand my father didn't step forward in an assertive way, like a responsible parent, and intervene when his bpd wife engaged in verbal, emotional and physical abuse of us children, and he set no rules or limits on her parenting behaviors. He was a very non-confrontational kind of guy.

When our mother/his wife would focus her rage on him, he'd take the verbal abuse for a little while, and he might yell back at her for a few minutes but then he'd just bolt, leaving the house to drive around for hours until she'd cooled off. Mother usually "cooled off" by screaming at and battering Sister and me; dad had escaped but she wasn't "done" yet.

Unless there is a responsible, mentally healthy adult in the picture, living in the home or at least living nearby who is both willing and able to set strict rules RE their bpd spouse's or ex's parenting behaviors, the children are basically screwed.

Children in such circumstances have no option but to develop very unhealthy coping mechanisms when their primary caregiver is emotionally disregulated, unpredictable (highly impulsive), engages in self-harming or other-harming behaviors, views the child as "all good" or "all bad" (or alternates between the two) and is paranoid and dissociative under stress.

My younger Sister developed big blocks of amnesia regarding her childhood and young teen years, and I lost my ability to feel my emotions. My memory is pretty intact, but I simply stopped feeling anything, for the most part. Now in late middle age, Sister and I are starting to remember and feel things more normally.

Just spending some time with a child, modelling calm, rational, joyful, mentally healthy behaviors for the child, reassuring the child that he or she is a good person, reassuring the child that he or she is not the cause of their parent's emotional illness, reassuring the child that you actually like the child and enjoy their company, telling the child that you believe in him or her, that you have no doubt that they'll do fine in life and can count on you for advice and support... that kind of thing will go a LONG way toward helping the children of mentally ill parents buffer their resilience and give them hope.