Let me just first get this out in open - I am very anti-smoking. I think you have heard from quite a number of people that can identify with how difficult it is to quit because either (A) they are or have been smokers themselves or (B) they live with smokers. I'd like to give you another point of view.
I have never smoked... NEVER. But at the age of 25, I was told that I only had about 40% of my lung function due to severe scarring of the lungs. I have been able to recover some of my lung function with a lot of hard work, a lot of medication, but I will never be at 100%. I've been told that i will most likely develop full blown emphysema down the road (if something else does not get me first.)
The only logical explanation for all this is my exposure to second hand smoke as a child. My parents did not smoke but my grandfather did. I should also add that I did not live with my grandfather, but saw him on a regular basis. I should also add that my grandfather died of cancer far too young. I absolutely adored this man, but I hate was his habit did to him and to me.
I am living proof that smoking doesn't just affect the smoker... it affects the people around the smoker. When my daughter was an infant, she could not even be near someone who was a smoker. The minute a smoker would pick her up, she would immediately start screaming, then gasping for air. That happened on numerous occasions. I'm doubt that happens with all babies, but it definitely was the case for her.
I don't know that your approach is necessarily the right one, but I can certainly understand it. I think I might have done the same thing if I were in your shoes. But like I said, I have zero tolerance for it.
The bottom line for me is that exposure to smoke is extremely dangerous for your baby. If your baby is exposed to second-hand smoke, it puts your baby at risk for lung problems as the lungs are still developing and far worse, SIDS. There are some more "understanding" folks who have posted here that would probably like to negate that, but those are the facts. Smoking, like any vice, is a choice. This may sound harsh, but your husband needs to quit being selfish, think about his family and do whatever it takes to quit.