I am not sure of all the rules on debit cards compared to credit card liability. However, one thing you can do is set the debit card limits low at the bank, ie $250.00 a transaction and $500 a day then they cannot drain it quick.
Also sweep money from the account into another that has no cards, so that the money in the debit card account only gets transferred as needed when you have bills to pay.
Fixed that for you.Single guys, don't get married!
Seriously, that sucks loud and hard! And I agree with the separate accounts. Joint accounts suck donkey balls.