Is a wife sinful if she acts upon her husband's denial that he uttered the word "taliq" (divorce), while she maintains that he did say it?

What is considered in divorce is the husband's statement, not the wife's. If the wife is doubtful about the matter, there is no blame upon her for accepting her husband's statement. However, if she is certain of a divorce that completes three pronouncements, then it is not permissible for her to allow her husband intimacy with her. She must use stratagems to free herself from him, even if it requires a ransom.