I suffered from some Gallbladder issues (acalculous cholecystitis) secondary to Chronic HCV so I can somewhat relate although your GB condition seems to be a lot more serious than mine was. Anyways, I just wanted to tell you I sympathize with you as I was in pain for almost 2 years behind it. After I treated the HCV my condition improved.
I think you are wise to get off the long acting pain medication because if this is going to be a lifelong condition that you have to manage you dont want to have a high tolerance where the pain medication doesn't work anymore. Having the medication for "breakthrough" pain seems ideal.
I also wanted to share that there is a Gallbladder forum here on MH as well where you may find others in the same situation OR you may be able to help others if you are interested. It seems like with all you have been through with the surgeries, you may be able to guide others just starting there journey. Just an idea anyway.
http://www.medhelp.org/forums/Gallbladder/show/1208
If you have difficulties while your detoxing...please post and Im sure many can help with ideas on how to deal with the symptoms. Wish you the best.
Always,
ABN