What should a woman do if she wants to get rid of the usurious earnings on her own money, but her husband threatens to divorce her?

The benefits from banks are forbidden usury (riba) which must be disposed of by spending them on charitable causes. The owner is not permitted to keep anything but the original capital. It is not permissible for a husband to threaten his wife with divorce to prevent her from disposing of unlawful money. She must dispose of it, even without his knowledge. If she is unable to do so, she must disobey him, because there is no obedience to a creature in disobedience to the Creator.