Re: Fireplace damaged from remodel...
Just a guess, but it looks like the broke into the chimney to run a furnace flue. You should have that inspected by a professional. If the flue pipe doesn't run all the way up and out of the chimney you are in danger of the furnace flue gasses cooling and falling back into the house through the fireplace. Carbon monoxide danger. You should never use one chimney for a wood burning fire place and a furnace flue. Adding an efficient insert with a double walled flue pipe may be feasible. But again check with a professional.
Be sure you live your life, because you are a long time dead.-Scottish Proverb