Questions for you (no need to answer):

Do you and your husband have the same bank account? Could you check his checking account, daily (most banks have a number to check balances, debits and credits)? Could he be placed on a strict budget with a limited amount of funds to access? Could you arrange with the bank to better monitor or limit his transactions?

Is he "having an affair" and spending the money on someone else? Is he using the money to purchase illegal substances or porn? Is he a chronic user of alcohol?