Thank you for your Question.
Im not sure what sin he wants to know of, but no one is obliged to discuss their past with their spouse. It is not obligatory for a woman to let her husband know of her sins and faults in her life before marriage. Hence, he cannot force you. (We don’t even encourage people to discourse their past after marriage)
You could use some help here, maybe a local scholar, friend or even an influential elderly, to speak to him and explain.
Besides all, Allah is most merciful and HE forgives as soon as his servant asks for forgiveness. Owing to this, InshaAllah, you are forgiven and that your past is neat.
As humans, we are only accountable to Allah swt and we should stick to this law InshaAllah.
In my duas