Welcome to SR! I'm sorry that you are having to go through this very difficult time. My AH was also addicted to codeine. I thought the lying and the hiding was the worst part, too, but that's a symptom of the disease. That's what addicts do! You didn't cause it, can't control it, and can't cure it.
I found a good article about how the family adjusts to the loved-one's addiction. I found it to be helpful, because it helped me understand that I wasn't to blame for what was going on. That my reactions to the craziness in the household were normal.
Family & The Relapse Symdrome - TLC The Living Center