Which event is symbolic of the "death" of Richard's relationship with his mother?

“My mother’s suffering grew into a symbol in my mind, gathering to itself all the poverty, the ignorance, the helplessness; the painful, baffling, hunger-ridden days and hours; the restless moving, the futile seeking, the uncertainty, the fear, the dread; the meaningless pain and the endless suffering. Her life set the emotional tone of my life, colored the men and women I was to meet in the future, conditioned my relation to events that had not yet happened, determined my attitude to situations and circumstances I had yet to face.” (111)

The night Richard’s mother tells him she wishes to die has a lasting impact on her young son, whose witnessing of her pain shapes his view of the world as an unfair place ridden with hunger and illness and his belief that life is about the struggle to overcome such obstacles.