Sounds tragic. Sounds like addiction. Addiction not only harms the addicts, but that those who love them. Her weight problem has gone beyond the point of vanity. She can't even drive a car. She is miserable, and it hurts him to see her this way. He's not disgusted with her, he's scared for her. And he's scared for himself. He's afraid that he is powerless to do anything but watch her destroy herself. They have children.

Unfortunately for him, he can't fix her. At this point, he need to decide to either accept her the way she is, knowing what struggles lay ahead or get a divorce. Heartbreak seems inevitable. Either way, reaching a point of acceptance will save him unnecessary suffering.