Final answer:
Children finding their mother's letters would likely experience shock and grief, leading to complex emotions and a shift in their understanding of family dynamics.
Step-by-step explanation:
Based on the excerpts provided, it can be inferred that the children's reaction to finding their mother's letters would be one of shock and grief. As is evident in the excerpts, situations involving secrets and the dead often elicit strong emotional responses. In one instance, a child is stunned by the revelation of a horrific act involving letters and consequently their father's drastic response. This would likely lead to a complex mixture of emotions including sadness, betrayal, and confusion. In narratives, children discovering secrets about their parents typically leads to a critical shift in their understanding of family dynamics and a reassessment of their past experiences.