Well, he can talk to her....  First, he needs to move as much money as possible into bank accounts held only by him (or even better, a trustworthy friend / relative) before talking.  Then he tells her that she used to be hot and then gave up on life and became a disgusting slob.  Then he tells her that if she wants him to be able to love her again, she's got six months to make major progress on fixing her shit or he's divorcing her.