OP he's simply swapped one addictive drug for one or two different addictive drugs. That's if he genuinely has stopped - which I would still consider highly, highly unlikely.
My previous partner was a drug addict. He could bare faced lie to me and either, I had an inkling it was a lie and chose to ignore (my dumb stupid fault - it's amazing what fantastical crap obviously made up 'reasons' you will fall for but I truly believe on all these occasions, I colluded with that lying by believing it). Or, he would lie but so utterly effectively that I 100% could not tell he was lying.
OP what you need to understand is he is spinning you lie after lie and bullshit after bullshit. You can't feel sorry for him. You have to force him to seek help. Now.
And you need to understand that in order to continue their addiction which addicts are literally terrified of not being able to feed, they will become the world's best liars, best manipulators you will ever meet. People you think you know who you think love you. But at the moment and for as long as they are addicts, they will never be honest and you will NEVER come first. Their addiction will.
And there's no grey area with any of this. He's either 100% off it - ALL of it, any drugs at all other than those prescribed and controlled by a physician - or he's still an addict. My XP used his drug of choice sometimes only 8 times a year. But it still completely ruined everything and that last time I caught him completely red-handed, after 5 years of lies and bullshit, was the day I ended it. I cannot tell you the utter relief that came from that moment to be honest. You don't realise what burden you're carrying round when you're in a relationship with an addict.
His still continuing to use off prescription drugs means he is STILL AN ADDICT. Even if he has kicked opiates (which I don't believe), you and he have moved literally NO steps further forward. If and when he finds he can no longer get the two drugs he wants now, he will go back to the opiates - or simply find something else.
He is NOT on the road to recovery and you OP, despite the real life experience-born advice you've received on here, continue to be completely in denial about the reality of the situation.