The Curious Incident of the Dog in the Night-Time- Post 2

After reading the letter addressed to Chrisopher from his mother in chapter 149, I was astonished when I understood that Christopher's father lied to him about his mother's death. A lie of this magnitude is not expected of a good parent, especially when it lacks proper justification. I understand why Christopher's father would believe the mother's affair and move would be hard for Christopher to accept, but did he honestly believe a feign death would be a good substitution? It seems that this lie is more to protect himself than it is to protect Christopher.