Under the circumstances, you will be better off to let a tax resolution agency work with you on this matter, rather than trying to deal directly with the IRS on your own. It sounds as though they are possibly trying to negotiate an "Offer in Compromise" on your behalf, which if accepted means the IRS would accept a lower amount than the entire $50,000 you say is due. They may also be trying to negotiate an acceptable payment plan.
The paperwork involved with these offers can be quite cumbersome. In addition, there are certain things that can help or hinder your chances of having such an offer accepted, and for that reason you are best to leave this in the hands of a tax consultant who has experience in this area, as it will increase your chances of having the offer accepted.
Unfortunately, even working with a tax consultant, these matters take time to go through the complete cycle. In the meantime, I know it must be an extremely stressful situation for you, but hopefully in the end they will be able to reach a settlement on your behalf.
Thanks for the question, and best of luck to you in getting this situation resolved.