Pitiful play against the Ponziani

The Ponziani is one of those openings that is rarely seen, which is why my opponent played it against me. Neither one of us knew the theory, and I think I got out of the opening OK, but I was outplayed badly in the middlegame. My opponent had already beaten me in each of our two OTB games, and was rated some 300 points above me, so I was pessimistic before the game even started. I would like to know if I could have played the opening better, what my mistakes were in the middlegame that caused me to have such a bad position, and whether there was any way to save my lost position. This was an OTB game, 90 minutes with a 10 second delay. When I resigned, I had 37 minutes left and my opponent had 13 minutes left. I have not done the computer analysis or looked at an opening database.