All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Accusing a Muslim of disbelief is one of the gravest major sins. The Prophet, sallallaahu ‘alayhi wa sallam, warned that anyone who claims that his fellow Muslim is a disbeliever or calls him an enemy of Allaah The Almighty while he is not, then this accusation turns back on him. [Al-Bukhari and Muslim] Accusing others of disbelief is not a matter that a person does or acts upon on the basis of his own personal reasoning. It is a matter for judicial ruling that should be issued by an eligible person who is qualified to do so.
Accordingly, you should treat your wife wisely, contact wise and rational members of her family so that they may advise her and reconcile both of you.
If that is not possible, you can resort to Khul'. It is an established issue under Sharee‘ah (Islamic law) that the Prophet, sallallaahu ‘alayhi wa sallam, ordered to take place when there is a need for it. On the authority of Ibn ‘Abbaas the wife of Thaabit ibn Qays came to the Prophet, sallallaahu ‘alayhi wa sallam, and told him that she did not want to live with Thaabit anymore because she absolutely hated him and feared that such hatred would lead her to do an act of disbelief or sin by disobeying her husband. The Prophet, sallallaahu ‘alayhi wa sallam, told her that [terminating her marriage] is conditioned with returning to him the dowry he paid. She accepted and accordingly, the Prophet, sallallaahu ‘alayhi wa sallam, ordered Thaabit to divorce her one single irrevocable divorce. [Al-Bukhari]
The issue should be submitted before a Sharee‘ah-based court in order to examine its aspects and issue a judgment accordingly.
Allaah Knows best.