As you said you have asthma then, a perpetual smoker is not good for your health. Even if she is your wife you have to look after your health first. You need to ask her to quit smoking or you can suggest her to smoke outside of your house. You shouldn’t delay this as its severely affecting your health. No matter how much you love your wife you should re-think about your health first. She should understand that smoking is leading you towards your death bed and it’s also not good for her health too. Thus, You should try to come to a conclusion mutually but to do that you have to confront her first.