Codeine is processed by the liver and it creates morphine. This is the true addiction. I think that the albeit brief reading of this thread the levels you have now reached need to be managed safely by a care provider who can give proper advice on tapering down and ensuring safe reduction.
Just to put this in perspective: my husband came off buprenorphine using codeine. Buprenorphine is a morphine/opiate blocker and substitute.
Can I suggest that you speak to someone in drug/alcohol dependency to get advice, I feel that this is a serious thing and don’t want anyone to be coping with dangerous and uncomfortable withdrawals. Good luck and sorry if I come across as condescending. Xx