Something SR helped me to realize is that it really wasn't about the drinking. It was about the behavior. So, if he drinks AGAIN, you will leave? He already drank AGAIN since he supposedly quit. If he gets in trouble with the LAW, you will leave? He's already in trouble with the law, hence his suspended license.
The message you seem to be sending is that his behavior is okay with you, as long as he doesn't get caught. Or maybe you just keep moving your line in the sand because he keeps stepping right over it?
L