Hello @12165008021954, I can only imagine the amount of pain your husband had endured in 8 years of constant pain. I know it has to be a difficult decision to make on whether or not to have the amputation to relieve the pain. I don't know if this article will be helpful but it does discuss what you and your husband are facing.
--- Complete Brachial Plexus Injury - An Amputation Dilemma. A Case Report:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5393136/.
Is your husband able to use the arm with the injury or does that increase the level of pain?