I have stated in several posts that Michael blamed Tom for not protecting the family. Tom's failing to do so resulted in Vito's near fatal shooting, Sonny's murder, and the decline in the family's position in the underworld. In addition, I think Michael resented Tom's having achieved a preeminent place in the family. In the novel it states that Micahel noted that in some ways Toma nd Sonny were even closer than he was to Sonny.
"Generosity. That was my first mistake." "Experience must be our only guide; reason may mislead us." "Instagram is Twitter for people who can't read."
