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, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

If a husband says to his wife, "You are not my wife," and other expressions which are a metaphor for divorce, then divorce takes place only if he intended it, however, if he did not intend divorce, then such expressions do not entail a divorce. For more, please refer to Fatwas 90531 and 90416.

Therefore, if a husband says to his wife, "You are not my wife," this does not lead to divorce if the husband did not intend it; however, if he intended divorce, then divorce takes place according to the number of times he uttered the above expression while intending divorce, whether he uttered it in one session or said, "You are not my wife thrice"; this is the opinion of the majority of the scholars . In this case the divorce is irrevocable and his wife is forbidden for him unless she marries another man [who consummates the marriage with her and then dies or divorces her].

However, some scholars are of the opinion that if a husband utters divorce three times in one session [by repeating the whole expression three times], or utters it once by saying, "You are divorced thrice", then this is considered only one divorce and he may take his wife back. According to this opinion, the husband may take his wife back during her waiting period or after her waiting period but with a new marriage contract.

Since the matter depends on the intention of the husband when uttering such a statement, then it is permissible for the wife to continue staying with him if he claims that he did not intend divorce.  

Allaah Knows best.