I say trust your gut. You know when things are off. As LumenandNyx rightly pointed out, normal drinkers don't hide their booze. So you needn't waste one more bit of precious energy trying to work out what's up. You know what's up.
Sadly, that doesn't change the fact that you have no power or control over him and his choices, only of you and your own. With the note and the concession that you should leave if you feel threatened or uncomfortable -- that's just plain manipulation. He wanted to drink guilt-free, and he decided the person who could give him that was you. You don't need his permission to leave if you feel uncomfortable or threatened! It's pretty presumptuous of him to think he needs to grant you that. When you didn't respond in the way he wanted, he turned on you, and tried to make his bad feelings all your fault. This is someone who is not currently capable of taking responsibility for himself--that doesn't mean you need to do it for him.
The question right now isn't really what do you do about him. It's what do you do about you. Is this the life you want?