The father is victim too.
He lost his son, and his son went from the perfect son (young pilot from the national airline) to a mass murderer.
He (the father) feel probably guilty about his son's actions, but he has nothing to do with it. And all Germany hates him now, and his wife (the mother) ass well, And all the Lubitz Family.
So, as a father, you can :
1- commit suicide (alone please)
2- deny the truth
3- go insane
He chose the second option...
I feel sorry for him