That's a tough situation, JSN9333. I admire you for wanting to be honest and open and above board with her.

I was trying to put myself in your place w/ her. I think if I were in that situation, I might try broaching the subject within the bounds of a counseling session, perhaps, since y'all are already going. I'd also make sure I said, up front and before you break the fact of your smoking to her, that you have been worried to death about telling her and fear that she may use this as a reason to leave you. That's a way of pre-empting and relieving some of the pressure of that topic up front, which is often a good negotiation tactic.

Another question occurred to me, and I hesitate to ask this but it's worth considering. Are you by any chance bound and determined to tell her now within the next two or three days because on some level--maybe not consciously but down underneath someplace--you're really hoping that this will provoke a falling out and potential separation? Just something to consider about your timing and feeling that this has to be done now.

I certainly wish you the best of luck.