I have been down a similar path, withdrawing from opiates and benzos, both at the same time and also separately. My problems with panic attacks, anxiety, depression and ADHD make the withdraw from xanax the absolute worse. I feel that all of the emotions, both good and bad, that have been suppressed for how ever long I was on those meds surface and an uncontrollable rate. I have felt just about every acute and protracted withdraw symptom that is listed for xanax and as a result, I would stop the opiates before the xanax because the acute tends to disappear a little quicker for me than the benzos.
What I have also learned is that very few doctors, either GPs or specialists, understand the severity of these symptoms. Focus has been given to alcoholism and opiate abuse, both "treatable" by writing prescriptions for a cross-tolerant drug and tapering down slowly. The thing about benzos is that tolerance can skyrocket out of control much, much faster than alcohol or opiates; you take too much of either and death is highly likely, whereas benzos can be taken by the fistful with basically no possibility of a lethal lose. This makes writing and maintaining a taper schedule extremely difficult for a GP.
Anyhow, I think I may have gotten a little wordy with that post. If you can find an addiction psychiatrist, great! If not, just try to be honest with your other two, give them a time frame for when you want to stop and stick to it. Veering off the schedule for even a few days can completely destroy your road to sobriety.
Good luck!