Just stay in the now. You were in a very tough situation: Relationship crumbling while he continued to smoke and drink.
And, no surprise, it makes the temptation to numb the emotions you are experiencing pronounced.
I think here is where the importance of sober support becomes imperative for many of us. I hope you have some sober friends around. When I was just shy of a year sober and letting someone slip through my grasp (I was very wary of the saying that addicts and folks in early recovery are tempted to take hostages, not get into healthy relationships) it was the support of others in recovery that kept me on the right path.
Take the high road (pun clearly unintended) in all of this. Remember the personal growth you have achieved and which is so evident in your posts here. Let go with love. Be honest with how important recovery is to you and that his continuous smoking and return to drinking is a clear sign of denial of his own problem and a slap of disrespect of yours.
I was in your boyfriends shoes when my wife got sober 15 years ago. I supported her, of course, because obviously she had quite the drinking problem. Pot was my drug of choice, and the craft beer was just to smooth out the edges. Pot was harmless, of course, and I saw no problem in smoking a joint in the morning before work, driving around the city on assignment and then smoking out to ease the stress at night.
Besides, it was just pot, right? Try to project your boyfriend's smoking out for another decade and you just might find someone like me, a hopeless addict, wrapped up in denial and selfishness and a near blindness to what I was doing that was in hindsight pathological. And smoothing out the edges with beer and wine progressed to 12 packs and half gallons.
You got this. I have no business saying the following, but many of us in hindsight find leaving one relationship and immediately chasing a new crush can have some serious drawbacks. If it's possible, once the boyfriend moves out, it might be great advice to have some relationship down time, let the cement of your sobriety cure a bit, dive deeper into the self exploration many of us find necessary at the one-year sober point so you can continue on getting comfortable with the sober you.
And do let go with love. Don't be tempted to bite back if he snaps and snarls a bit. And perhaps for his own sake down the road, point out that his rejection of sobriety could bode serious consequences down the road for him. Maybe, just maybe, he might be able to see through the haze of pot that he in essence placed his "not a big deal" pot habit before you.