I think no contact is a great idea - but that means NO CONTACT - no calls, texts, email, talks to friends, monitoring of Facebook/email/bank accounts, interception of mail, delivering messages to/from him for others, interogation of mutal acquaintances re: his behavior, no quizzing his family members - N O T H I N G.
If he is your ex, why do you have access to his debit card account? He is a grown man on his own. You are not his mommy! He can spend his money any way he likes even if it means getting drunk because he is NOT your reponsibility. It is really hard at first, but I think you will probably feel better for it in the long run.
JMHO....