I still maintain my point, though. A family relationship, no matter how bad, will still be there, even after being cut off.
Even after the other party has passsed away.
It continues to color your life, your decisions, your reactions. Even to the point that acknowledgement, getting help (non necessarily professional) and, eventually the ability to cope and continue your life can come from it.
Hmmmm. I'm not entirely sure how you mean that. Obviously anyone who was involved in your upbringing will have had a major effect in your personality and any "issues" you have, but that doesn't mean there is still an active relationship there (which may not be what you mean, but is how I read the first sentence.)
WARNING: Prepare for utterly un-QC related rambling. 
I no longer have contact with my father, and the only influence that has had is to remove a major source of stress. I would have cut off my mother years ago if I did not wish to be around for my young (9 & 11yo) siblings. Enough pushing will remove your ability to love or truly care about a person. I feel protective of both my parents and wish them to be happy. That is all.
Bear in mind that abusive childhoods are both common and infinitely variable. I have a friend who was sexually abused by her step-father, uncle and grandfather, another whose father used to beat her until her gums were black; another whose father used to beat her mother until one day his "friends" beat him to death to steal his weed (his heart stopped; he lived, with brain damage), and another whose father successfully accused her mother of sexual abuse to get custody, then gave her back when he got sick of parenting. These women all have different coping mechanisms, and different relationships with their family.
My childhood was not so spectacular. In between teaching me to hate myself, my parents were encouraging, femininst and so so sorry for the way they treated me. We went to counselling sessions together from when I was in primary school. My mother would come crying to me about what a fuck up she is and she's so sorry for how she's treated me, and I would talk her through it.
So you see, I'm not 100% sure what your point is. There is vestigial caring in me for my family. I am sorry for how shit my parent's lives have been and want them to feel better. But I do not have, and am beyond wanting, a relationship with either parent. In the ups and downs of my upbringing I dissected my feelings and treatment to the point where there is no more to get from it. I will work through my problems as best I can without parents.
I do not see that familial relationships, despite being harder to break, effect you any more long term once broken than a once-close friendship.
/ramble.
