Honesty and trust are vital in any working relationship, my advice is to prepare yourself for the worst. You're living in secrecy, you're not being yourself. Tell her and attempt to persuade her it's not as bad as the media and government claim. There are plenty of studies that are pro cannabis. If she does ask you to make that choice then i wouldn't choose her, she should accept you for who you are, if cannabis makes you happy, then smoke it, regardless of anyone. You may be married but you should 'live for yourself, there's no one else more worth living for.'