A.B.
Such wonderful news that he is ready to quit. I was a smoker for almost 20 years and have now been smoke-free for 16 months. I quit with the Chantix pill. I too was ready to quit. Have him write down the reason(s) to quit and post that somewhere where he will see it every day. Mine was to not be tethered to cigarettes any longer and be able to enjoy a day without wondering when I would be able to smoke.
I would recommend to keep a lot of fresh fruit and/or veggies cut up and easily available. Pretzel sticks also helped; it is the hand-to-mouth action.
Also, be supportive and understand that his mood swings are not necessarily directed towards you. Go for nightly walks or some other activity that you can do together, this will help keep his mind off of when/where his next cigarette is.