A few books popped into my head when Laura asked this question:
The first book is Pete Walker's
CPTSD: From Surviving to Thriving: A guide and map for recovering from childhood trauma.
He writes that the human brain evolved during the Hunter-Gatherer era, and we still have this basic formatting. In earlier times, even a few seconds without contact with the parents set off the infant's alarm bells, as a predator could easily attack and carry off the child as prey. Children today feel parental abandonment or neglect as a looming threat of death. And in cases where the parent is actually the predator, the situation is even more tragic. He calls this process 'soul murder'.
We're too young to realize our parents are at fault, and we are adaptive, so we assume it's OUR fault. But no matter what we do, it doesn't seem to work. The result is developmental trauma, which actually changes in the physiology of the infant brain. I see it as sort of like the carving of a massive self-hatred superhighway through the ecosystem of our grey matter. This becomes the default route for our sense of self and relation to the world. Other routes leading to self-compassion, self-observation, and self-expression, as well as confidence, curiosity, and joy, are not travelled as often. When we're older and start to develop a degree of consciousness, we can start to notice this aggression against the self as the vicious inner critic, or the negative introject, whose sort of like the the CEO of the hatred superhighway.
He goes into a lot of detail about it all, including the realization that when we have panic attacks, they are often flashbacks to this terrorized infant state, a feeling of dying or being killed or imminent death that can come out of nowhere.
But the most important part of the book to me is focused on treatment. The first is psychoeducation - reading about CPTSD, childhood trauma, etc., as well as exploring one's childhood through journaling, etc., and doing some personal archaeology to see just how bad it was. This achievement of insight is painful, but important.
The second part is shrinking the inner critic through a series of internal battles. This is done mainly via conscious use of anger as a form of mental blocking. It's basically redeveloping a healthy 'fight' response, learning to assert ourselves and take control over the forces of destruction within our own Being. It is a great challenge, but we can make use of the strength mentioned by the C's, and in my own experience it is doable with persistence and effort.
So we can use the energy of the self-hatred superhighway against itself. Luckily the brain is plastic - nothing in us is set in stone so long as we strive to heal. And, so very crucial in all of this, is to be willing to feel all the catastrophic hatred one has of one's parents, without any excuses and no holding back. The anger is first directed at the inner critic, and then also towards the ones who tortured you, and in so doing it becomes this sort of protective righteous anger. Or at least that's how it was for me.
Another book that helped with reaching those levels of the subconscious mind was
Making Peace with Your Parents. It details active exercises in getting all the resentment out of the body. It also works with parents who have gone to 5D. Although the title includes the word peace, it's more like
'Making War On Your Parents'. Or that's how it was for me. Anyways, very good stuff.
Third, we can also flood the superhighway, by making use of conscious grieving.
This corresponds with mythology - tears are curative, transformative, and full of life-giving properties, similar to how rainfall brings life to the barren landscape. I feel that grieving brings the Water of Life to those places in our grey matter we weren't allowed to travel to - the hidden valleys of self-compassion, self-confidence, and self-expression. It's in these places of abundance where our 'souls can fully manifest', or so I think.
There's a caveat, though:
He mentions that the inner critic is sometimes so hostile to grieving that it may just end up beating the crap out of you for crying, for being weak, for feeling anything at all. So shrinking the critic may need to be your first recovery priority. He worked with many clients who were way too traumatized to grieve, and so they spent months working on shrinking the inner critic so that grieving could happen without setting off a toxic cycle of internal judgment.
I've found that only after angering at the inner critic, shrinking it, then angering at my parents, then drawing sharp boundaries with them, as well as grieving, was I able to fully express myself and communicate with less fear. I still practice external considering with them, but I don't put up with their BS anymore.
I can't say that I've totally deprogrammed, but these two books helped a ton to reach those subconscious levels sometimes. I was often surprised to hear the primal screams and sobs coming from myself when doing this work. But it always felt better afterwards. Taking time in meditation to seek out the all the dark, hellish material helped to get to there, too, to bring whatever light and love I could to that place - as well as other modalities like somatic experiencing and/or body sensing, as well as regular journalling.
You'll know if you've resolved it, believe me. Everything changes.
Go raibh míle maith agat! 
