What should I do if, while leading my wife in congregational prayer (jama'ah) as imam, I remember during the prayer that I am not in a state of purity (wudu) or that my wudu has been nullified? And does my wife continue her prayer or not?

When a worshiper recalls or experiences an invalidating event during prayer, he must interrupt his prayer, perform ablution (wudu'), and repeat the prayer. He is not permitted to continue it. If he is an Imam, it is recommended for him to appoint someone to complete the prayer with the congregants; otherwise, they should pray individually or appoint one of them. In the case of the question, the wife completes her prayer individually.