Is a husband's jealousy over his wife, when her brother-in-law enters upon her without permission and does not lower his gaze from her, and his insistence that his wife stay in a separate dwelling when her family visits if there is a non-mahram man with them, considered an injustice to her or a legitimate right?

What you requested from your wife regarding her modesty in dealing with her sister's husband, and your jealousy over her, is not an injustice to her; rather, it is a praiseworthy jealousy. We advise you to seek Allah's help and discuss the matter with your wife wisely, explaining to her that your jealousy over her and your concern for her protection are signs of love and honor for her. Indeed, the Messenger of Allah, peace and blessings be upon him, was jealous over his wives, and they were the purest of women.