First of all we recommend that you “Invite to the way of your Master with wisdom and good admonition, and strive with them in a way that is best” (16:125). Those who really intend to understand these would listen to you. There are also a type of them who intend to perturb the real believers using such tricky questions and make them revert from Islam. They would not listen to you how much you try to explain. Your duty is to manifest the truth.
According to the Qur’an, the wives of our Prophet are the “mothers” of believers and it is ruled that nobody else can marry them. The Glorified Allah commands:
“The Prophet is more valuable for the believers than themselves, and his wives are their mothers.” (Al-Ahzaab/The Allies 33:6)
“… You don’t have any rights to pain to the Messenger of Allah. And also for ever, you are not allowed to marry with his wives after him. Because that would be an enormity in the sight of Allah.” (Al-Ahzaab/The Allies 33:53)
They are declared as mothers of Muslims, and marrying one’s mother is enormity for everyone.
About the marriage age of Hz. Aisha and marriage of children, please read the following articles: