He said to his brother-in-law “Your sister is divorced.” Has divorce taken place?

No File Exists
Check below answers in case you are looking for other related questions:
It is not a condition of divorce that the wife should know or that she should be divorced face-to-face
Affect of Change of Name on Divorce

No File Exists
Related Answers:
Guidelines on what constitutes consummation of the marriage and ruling on divorce of one whose husband has been alone with her, at the time of menses
He gave her a conditional divorce that would become effective if she spoke to her sister's husband, then she spoke to him without meaning to
He divorced her three times when she was menstruating
It is not a condition of divorce that the wife should know or that she should be divorced face-to-face
Affect of Change of Name on Divorce

Recommended answers for you:
Keeping a dog, touching it and kissing it
Advice to one who does not want to get married
Circumcision: how it is done and the rulings on it
Praying at graves and the conditions of intercession
Is it permissible for husband and wife to remove their clothes when sleeping? What effect does that have on tahaarah (purity, cleanliness)?