Seems to me you are looking for a sounding-board...I'll echo the good advice above...tell her what you are doing...but this is falling far too short. You say she has a negative (accurate) view of drugs, and understandably so. After all, the context here is marriage & starting a family...RIGHT??? You knew from the start she will not be agreeable. Your decision is already made, because you decided to go with the lady instead of your obsession with drugs. So there you go. Next you blabber about how you don't miss drugs and if it comes down to it, you'll choose your lady.
You already did chose your lady...now it's time for you to not be missing the drugs (is this not what you said you can do...will do etc )...add to that the already mentioned opiates...I especially point to your listing of drugs...it reads like a child's wish-list...
Why you don't know how to talk with your wife? Let me tell you why you're asking strangers about how to have this conversation with your partner....because you are being dishonourable. Sure there will be some of like-minded people making comments that you can cling to, in your lame effort to feel better about a rotten thing...that's why you're here, isn't it..."Hey guys, I need some tricks on how to shaft my partner into smiling and agreeing whilst I make a world-class Idiot of myself"...oh yea possum, top class...
Ever thought about counselling? I'm guessing you're still a long way from a smart idea like that...but it will come to you...I just know it will.
Let's look at your plans to be sloshing around on opiates (or whatever) once a week, and sitting on your ass recovering on the day off...sounds pretty lame mate. How would you go selling that one to your partner? I could be wrong, but I'm guessing she wants a husband who is emotionally available on his day off, not some self-absorbed lump sloshing around the house...staring at the wall...
In case you really haven't a clue...and I can see you don't...even if she was open to drugs...in partner relationships, drugs are highly corrosive...yes yes there are people who win at lotto... You will certainly lose. Building a loving, trusting, caring, healthy & intimate relationship should be your pet obsession, not frigging drugs...if I was a prick, I'd be telling you what a fucking idiot you are...but I'm not like that...fortunately. It's better we encourage you to stand up like a man, because that's what you're supposed to be. Not a delinquent child inside an adults body...no. A man on the inside...the man your partner is relying on.
Listen mate, you need to pull your head from where it should not be stuck, and think about how to best catch up the last 5 or so years you forgot to grow up, because what's coming your way is a whole bunch of responsibilities you ain't fit to even look at, let alone handle them in a responsible way. Seriously, if I knew you personally, I'd be telling you exactly what time it is...
I hope you reply, and don't be holding back with the whining and excuses...your rationalisations, justifications...it's ok. Be rude curse me, swear me... whatever...I understand if you feel offended...I expect you to feel offended...it's all good, only don't run back into obscurity, sneaking around entertaining secret plans to start your slimy little double-life with maybe the help and good advice from some seasoned druggies & partner-abusers...
Best wishes...I mean you no harm.