Do you trust your spouse 100% when it comes to finances even there's already a history of dishonesty?

I think there's a right to be a little skeptical if there's a noteworthy past of dishonesty. Maybe you could express that you're a bit doubtful just because of the past, and that you want to go about addressing all financial problems together?

Honestly, even if I try to trust them again, I would find it really difficult. Trust is very hard to mend.

It's difficult to do that. Pero you have to help him correct his mistake. After all, you're ONE.