Forcing divorce on a mentally ill wife

Shulchan Aruch(E.H. 119:6): A woman can be divorced against her will. Rema: And even if he doesn’t have money to pay for her kesubah and dowry – she cannot prevent the divorce because of failure to pay her money she is due. Rather they can be divorced and then she can go to beis din to make the financial claims against him (Rosh, Rivash). All of this is according to the Torah law. However Rabbeinu Gershom decreed that a woman cannot be forcibly divorced – as we explained before (Shulchan Aruch E.H.115).

And even if he is willing to give her the kesubah he is not permitted to forcibly divorce her today. Nonetheless if he transgresses the decree of Rabbeinu Gershom by forcibly divorcing her and then he remarries – he no longer can be called a sinner. ... If she develops a blemish see (Shulchan 117) whether he can forcibly divorce her. Some say that if a mitzva is involved he is able to forcibly divorce or he is permitted to marry two wives. Shulchan Aruch: Therefore a child can be forcibly divorced even though she isn’t considered have full intelligence and even if her father accepted her Kiddushin which is Torah. This is also true of a deaf woman who was married when she could hear and the later became deaf. However if she becomes insane – and doesn’t know how to protect it - she cannot be divorced until she recovers. This restriction is a rabbinic decree in order that she shouldn’t be abandoned to immoral people since she is not capable of protecting herself. Therefore while she remains his wife, he can leave her and he is permitted to marry someone else. Nevertheless her food is paid for from her money and he is not obligated to provide her with clothing or sexual relations. He is also not obligated to cure her physical ailments (Some say that he is obligated Beis Yosef citing Rashba.... and this view is the dominant one) or to redeem her if she is captured. However if he does give her a get despite the prohibition, the get is valid – as long as she knows how to protect it. Rema: (Some say that even bedieved it is not valid). In the case where she is sometimes insane and other times is lucid and she is divorced when she is lucid because she seems have stabilized - then the get remains valid even if she relapses. Shulchan Aruch: And he sends her from his house and he has no obligation to deal with her anymore.