Zaid Alsalami, Shaykh Dr Zaid Alsalami is an Iraqi born scholar, raised in Australia. He obtained a BA from Al-Mustafa University, Qom, and an MA from the Islamic College in London. He also obtained a PhD from... Answered 4 months ago

Bismihi ta'ala

It is wrong for your wife to pry into your past sins, and if it has nothing to do with your current life or has no involvement with your marriage, it is haram for you to disclose it to others. We are not allowed to expose our previous sins to others, or confess to anyone about the past, especially if we have repented. 

She should refrain from asking you about it, and you do not need to lie. You just refuse to give any information about it. 

With prayers for your success