Is she sinful for making her husband choose between her and his second wife, knowing that he does not desire her, cannot tolerate her, and is seeking to divorce her?

It is not permissible for a wife to ask her husband to divorce her co-wife, due to the Prophet's (peace and blessings be upon him) saying: "A woman should not ask for the divorce of her sister to empty her plate." Nor is it permissible for her to refuse her husband's bed for this reason, as it is a forbidden act of defiance (nushooz), unless she has been subjected to injustice or harm, in which case she may request the removal of the injustice. Jealousy between co-wives is a natural human emotion, and a woman is not held accountable for it. The wife should fear Allah regarding her co-wife and advise her husband to be just between his wives and not oppress any of them. The husband must be just between his wives, otherwise, he will come on the Day of Resurrection with one side of his body drooping. The questioner should repent and seek forgiveness if she has asked for the divorce of her co-wife or has been defiant because of her husband's marriage.