Relationship with our DD has greatly improved in last year and she lives out of state, but she did ask me if there was any way I could accept some responsibility for the breakup between my parents and I
I get this from the few relatives with whom I still speak, and they don't get it. None of them lived in it, and like you, I got hit with it from both parents, as an only child alone in the house with them. The worst is my half brother who is older, was adopted at birth, and didn't meet our shared mother till he was already 36 years old. He only sees what she just can't hide, but was never enmeshed, never her caretaker, her emotional supply, her scapegoat, her chance to remake herself.
My half brothers who my dad abandoned as children to create family #2 with me and mom sometimes ask if I will ever reach out to our 'father'. I finally had to in no uncertain terms describe the literally black and blue beatings I'd get as a child as young as 3, with a belt, that would keep me in long sleeves and pants to hide the marks. And how it went over the years from physical abuse to psychological manipulation and control. He got quiet and stopped asking.
I am scared about what I will do when I learn they are either going of gone. One lives in another state, mom, and the other is 30 miles away. I've been NC with them and most of the FOO for years with one and almost 2 decades with the other.
Sure, I am responsible for my decision to keep what I need as a buffer/barrier between them and my sanity. But as the minor child for the majority of the relationship, 2/3 of my life before I was fully NC, I cannot accept any responsibility for their choices that made my buffer so necessary.
I get so upset at times when people ask this "can't you just get along with them / forgive them / get over it / etc." If it was an ex-boyfriend who treated me that way, at all, for even just a few months, no one would bat an eye at my never talking to him again. But use the word "mother" "father" or "parent" and suddenly all of that goes out the window.  :)NA and family ties ARE important. But they should not and cannot supersede more than a reasonable amount of MY mental and physical health. If grandma is rude about my apple pie every year - ok, that's one thing, it can be ignored, dealt with, whatever. But if grandma made fun of the pie, had beaten me as a child, told me I was ugly and worthless as a teen, told me I'd never amount to anything, was no good, raged at me, neglected then smothered me, used me, then WHY should that be okay just because she had sex once and passed on her genes?
Family entails more than simply passing on genes or living in the same house. I learned this at my 30th birthday, when I ended up crying for a bit in the bathroom. I felt horrible that I was turning 30, and that my friends had done so much for me, and yet NO family had even sent a card. I was in LC with mom at the time, and the 3 half brothers, cousins, even a few aunts were still in my circle. But H's family and our friends were the ones there for me. Anyway, a friend found me and asked what was wrong. I told him, "I am sad I have no family, don't belong anywhere." He simply hugged me and said, "WE'RE your family." And it's true.
Anyway, this is long, sorry, but no, people who can't and won't understand the need for LC or NC often resort, maybe unintentionally, to guilt to make us initate contact.