Does having anal intercourse with my wife, with my knowledge of its prohibition and her consent, invalidate the Hajj I performed previously, and what is the expiation for this act?

Having intercourse with a woman in her anus is forbidden. You both must repent, feel remorse, and seek forgiveness for this heinous act. There is no specific expiation for it, but good deeds erase bad ones. This act does not invalidate the Hajj, and there is no need to repeat it.