Why does Ashpool kill his wife? How does her death affect the family?

Ashpool kills his wife when he finds out that she has planned a strange new direction for the family. The idea she has is to form a symbiotic relationship with the AIs she has commissioned, a relationship which will allow the family to live forever. Ashpool cannot accept this, so he strangles her. Marie-France's death causes the family to hide within itself and become reclusive.