Hey Mick,
You have such a lot of 'big stuff' to deal with. You really do need to get some professional help with this and I think your girlfriend might be the one to help.
I am no expert. But it seems to me that you have one hell of a big op coming up in three weeks - there is one thing that is going to make that a hell of a lot worse - going cold turkey at the same time and hitting withdrawls in the ICU and recovery - I am not a doctor, but I am pretty sure that this is not going to do your remaining kidney or your liver any good. It is also going to have your pain receptors screaming for drugs - the narcotics the medicos are going to be giving you (what they will legally be able to give you with their pain relief protocols) probably won't be hitting the sides of what you will be needing for pain relief coming out of such a big surgery- unless you do this NOW and get clean before surgery. You are a fighter. Someone or something in this universe wants you to be here - otherwise you wouldnt of made it when you fell off that building, or when you have been through all the other crap in your life - YOU have to believe it and YOU have to do whats best for you. No one says it is going to be easy, you of all people know that life isnt all rainbows and butterflies, but only you can do something right now to help you get through this - or at least make it a bit easier. Just wanted to let you know that I am thinking about you and that the ball is your court right now - there are people out there that want to help - you mentioned your family - it sounds like you don;t want to worry them, maybe they want to be worried - they probably already are with everything that is going on.
Thinking of you.
Nicole