Xanax is similar to opiates in that it makes emotional pains and problems go away, the difference is it does this by sedating you rather than giving you overwhelming pleasure.
Apparently benzodiazapine (and alcohol) withdrawals are the worst you can have. I’ve only experienced benzo withdrawals, so I can’t say, but it’s worth remembering that if you just stop using them cold turkey, you can actually die, unlike practically every other withdrawal.
So just remember he’s going through some stuff. Don’t let that be an excuse for him to take advantage of you though.
They can’t fry nerves or anything? My Grandmother has spine issues related to an accident and had that done a few times, so perhaps it’s something you could ask for? Sorry to hear you’re going through the pain though, I don’t think most people realize how awful chronic pain is.