[MRM]

As a practical matter you don't have to worry because your scenario will never come true unless he is a particularly moral and ethical person. Why would he divorce his wife when he can live with another woman and have all the benefits of marriage with none of the disadvantages of divorce? In other words, he's highly unlikely to get divorced. Why would he? He doesn't need to get married.

But to answer your direct question, the putative ex would get a guardian ad litem appointed who would look out for her best interests during the divorce. She would get whatever she is legally entitled to and it would all gonto her care in the locked nursing home ward.

Seriously, she isn't there anymore. She doesn't have the mental capacity to know where she is or what she's doing. The best that can be done for her is to keep her comfortable, have caregivers who cooperate with her flashbacks, and keep her as physically healthy as possible. All you can ask of him is to keep taking care of her, honor her memory and try not to embarrass himself now that he's alone.