What is the ruling on photography and the overt display of adornment in the pictures of my wife that were taken at a mixed wedding?

Among the necessities of faith is a servant's protective zeal regarding Allah's sacred prohibitions. You are right to be angry about your wife's immodest display (tabarruj) and unveiling (sufoor), if that is indeed proven, as she is committing a wrongdoing by doing so. It is not permissible for her to display her adornment in front of non-mahram men, and the matter worsens with the mixing of women, their dancing, and their being photographed.

You must advise your wife to repent and not return to such behavior. We also advise you to be diligent in teaching your family matters of their religion and raising them upon faith, and that you yourself be a role model for them in goodness.