The correct answer here is very simple. Why havn't any of the 'legal eagles' here given it? Hmmm.
Point 1...If you go to court you will LOSE unless you can prove that the charges were fraudulent and/or you are past the statute of limitations (doubtful). You will likely be on the hook for the full amount plus penalties, court cost, etc.
Point 2...Do NOT hire one of these companies that advertise to negotiate a settlement for you! You will be commited to paying the negotiated settlement PLUS whatever fee your go-between charges.
Solution...Talk to the creditors and negotiate a settlement YOURSELF! It's really quite easy. They would much rather avoid the cost of court and follow up for pennies on the dollar. Subsequent debt collectors will only pay 5-10% for the rights to hound you. Simply ask them what it would take to make it all go away.
My experience...When I was going through my divorce years ago, there were several joint credit cards and a few my wife held without my knowledge. The bills went unpaid for months as we fought and began divorce proceedings. I simply told the creditors I didn't have the money to pay due to the impending divorce. They practically BEGGED me to settle for 20% on the dollar. I borrowed enough cash to do so and make it go away.
I may have been able to get it done for less but was glad to make it go away. My credit was fine within a few years once I showed I was 100% reliable as an individual and my crfedit report showed "settled" (or something similar) for past joint debts.