I Have Been On Many Prescribed Drugs For Many Years

I have been on many prescribed drugs for many years due to bone disease where I have an enormous amount of bone cysts (pain) emotional issues (depression). I saw a toxicologist who is recommending that I go off the drugs as I find myself taking more than prescribed. I take valium, fentanyl patch, oxycodone, and thee others I have taken myself off. Two years ago I had 1/2 of my liver taken out due to a grapefruit size cyst. I am trying to wean off of the drugs with major side effects. My question: should I be hospitalized during this time as I do have withdrawal side effects which include shakes, hot and cold body temps, panic attacks, etc. I would also like to know how long these drugs remain in the bodies system.