Deejjay, what if you leave, quietly and without slamming the door (I realize you would not do that - just trying to be thorough ), and pin a note to the inside of the front door or put a sticky Post-It note on it with your message. Exactly what you said - "I am going out, ..." etc. but in casual hand-writing.

Then there is no possibility that your voice might tremble as you talk, giving away just how anxious and upset you are. no, nor would be possibilities for other ways in which he might interpret the tones of voice in a bad kind of way.

You know that money has no smell - well, little handwritten notes have not much smell, either. You can add a happy face at the end, or a . Or you can text him from outside with a short "went for a walk. we can talk later when both of us are calm".