If the husband is totally impotent and unable to penetrate, then his wife has the right to seek divorce through the Haakim Al-Sharee'ah who is the Marji' of Taqleed who gives the husband one year to treat himself. After one year, if husband is still unable to penetrate, then the Marje' of Taqleed issues an order of Faskh which mean nullifying the marriage.
'Wassalam.