The reason why he simply does not divorce her is some life insurance money he is going to get if her gets to kill her.
I hope Hell has a cavern hot enough and deep enough for this rotten devil to go to once he meets his own end!
If they allow him to have his way it should have the following stipulation. Once they pull the feeding tube he can not have food or water until she passes away. Maybe then he'll realize what an a$$h*le he is and the suffering he put her through. It might be enough to make him change his mind and for him to take a different course of action.