From reading this (and only getting your side of the story) I'm thinking you are the one suffering from depression. Your wife seems to have addiction issues. I'm not sure why you married a smoker if you get sick from the smell, must have made dating hard. Speaking as a former smoker, I can tell you that a smoker will quit when THEY are ready to quit and not one second before. Also, it takes the average smoker 7 tries to quit. If they ever do.
Have you tried Al-Anon? It's a great resource for people who live with alcoholic/addicts. Your post sounds like you are working really hard to change your wife. That is just a waste of time. You can't change another person. You can only change your decision to put up with what they are doing.
There are a lot of nice people on here you can vent to, and that can help a lot. I'd definitely talk to a doctor about your depression and maybe get some counseling.
Chronic pain, Depression, Fibromyalgia, Tennis Elbow (both arms), Arthritis (knees and fingers), Diabetes. Ruptured disk L-4, Severe degenerative damage L5-S1, ACDF C6-C7