Hi breather,
I love your addiction insights. I don't think it helps us to pretend that nicotine addiction is any different than addiction to the "bad"/ illegal drugs. Addiction is addiction, with all the physical and psychological components.
Learning how to maintain our own headspace and happiness without the addictive chemical is, indeed, critical to moving on. I have been coming to the conclusion that happiness is not necessarily a joyful or euphoric state (although I can sometimes get those, even without the chemicals). Instead, it is more like having perspective and hope, regardless of whether the present moment is and up or a down one.
I'm envisioning a little fishing bobber atop the water. There will be calm days, and stormy days, sunny days, rainy days, etc. We can't change that. All we need to do is keep on floating with the knowledge that "this, too, shall pass."