re: If I sold my house, do I have to show it?

You probably could have done a 1031 exchange but likely too late for that given you sold it last year and there is a 45 day window from sale to ID new investment properties and 180 to close on it.

How much did you pay for the place? Or if inherited what was value when you inherited the property. That's more relevant than the mortgage balance at time of sale. If you sold for $80k doesnt seem like a ton of room for capital gains. I'd ask an expert.