Has your doctor explained this to your wife? Honestly, if he hasn't, I'd set up a "family" visit with an authority (your doc) who may be more effective at quelling your wife's fears, and she may be more open to vaping then.
With that said, if she's read a negative study or two in the news (they can be pretty distorted and terrifying) her concerns are probably that she will lose you faster, rather than any actual knowledge about vaping. So, you can consider it a sign of caring, but perhaps help her feel reassured about vaping and how it is, or is not, affecting your COPD. Also, there are may positive vape researchers and articles that it might be helpful for her to read. She may find that reassuring as well.
In my family, male, female or kid, we all wear pants, we make decisions together when necessary, but we also do our best to be kind, compassionate, and keep our distress to ourselves when one family member may be doing something that we may not agree with, and that's the only way to go in my opinion. So, the best thing you can do for both yourself and your wife, is to let her hear it from the DOC, in person, that it is safer for you to vape than resume smoking.
Best of luck, I hope your wife comes around.
Anna