My cannabis use is a core part of me and if you don't accept that well your never going to accept me.
I think that question is the one OP truly has to answer. If it is, then it doesn't matter how much he's in love with his wife, she isn't in love with him, but with the man she wants him to be. If it's not part of his core being, he should quit and never look back. People act as if it's somehow a minor point and that love will conquer all. The core of your being is never a minor point. Very few couples succeed when their core beings are in conflict. 'Love conquers all' is a nice sentiment, but hardly ever true.
Yes, people are more important than getting high, but that core compatibility is the most important thing in a marriage. If getting high is in OP's core character as it is in me, the poster above, and many cannabinoid users he wouldn't be leaving her for pot, he'd be leaving her because they're not truly compatible.