If someone asks a question to us which might expose our sins, how do we tackle it? If saying we aren’t comfortable would be a giveaway, can we lie our way out of it?

In another case, if it’s a potential spouse or their parents, are we required to mention it?

If one can bend the truth, it’s better than to expose their sins. There are certain things that a spouse should know, and one has to tell them.
Not necessarily past sins but things related to physical ailments or mental illness or virginity for girls