Debt collection after foreclosure and sale

by Jenifer
(St Johnsbury, VT (USA))

I received a letter from a debt collector in regards to a large remaining balance from our home foreclosure sale (over $100k). This year I claimed close (difference of about $6k) to that amount as income on my taxes. I was informed by "the block" this would resolve the debt as paid. Do I still owe this debt? Any idea why the amounts would be different?
Thank you