Denial is a self-protection mechanism. It has a very useful purpose--to protect us from things we are too overwhelmed to deal with. It can, however, become a problem when the initial shock subsides and we still cling to it.
Your story reminded me of one time when my sister and I were visiting my mother. We went to the grocery store and walked by a car in the parking lot with two unsupervised children in the car. My mother expressed her disgust and judgement over how a parent could just go in the grocery store and leave her children in the car. My sister and I looked at each other in shock and amazement, both remembering all the times she and my father left us in the car for hours at a time while they were in the bar. My mother still does not see the disconnect in her laughable self-righteousness.
There is no breaking through another person's denial. You know the truth and you are uncovering it and working through it. Difficult and painful as it is, your life will be better for it. Days like the one you had today are hard, to put it mildly. But it's so much better than denial.
L