Roberto Mancini's side looked set to let slip a first title in 44 years on the final day of the season, with bitter rivals Manchester United on course for a record 20th crown as City struggled against embattled QPR.
However, things at the Etihad Stadium are never straightforward and late goals from Edin Dzeko and Sergio Aguero helped turn round a 2-1 deficit to rescue City - much to Hart's relief. He said: "I was a lost soul at 2-1. I totally didn't know what to do. I was on the pitch, but I had no input whatsoever over what was going on."
He added: "I was trying to get myself up front. It's a good job I stayed out the way because I would have probably got in the way.
"When Edin scored I thought we might get one chance, but the way things had gone I thought 'so what? Someone will block it or something'.
"And then it went in and I don't really know what happened. I had to look back. I was just a fan on the pitch willing the ball to go in the goal and when it did all hell broke loose.
"Football-wise it was the worst and best that can happen to anybody, definitely. I was lost. I didn't think we had lost, but, personally, I was lost because I didn't really have any direction or input in the game. Luckily the boys pulled through and it just felt - well, I don't really know what it felt like."
England team-mates from the red side of Manchester are also probably still trying to get their heads around the season's finale. Hart revealed he has spoken about it with England team-mate Wayne Rooney, but will not be aiming any playful jibes at the striker or any other of his United team-mates.
"I've watched it a couple of times since because I wanted to know what happened," he said. "I didn't know. Apparently we won. I haven't watched it with Wayne - that wouldn't go down too well!
"It's not something you banter about. I wouldn't want it bantered about to me. We talk about it, but no, no banter. It means the world to them, just as it does to me so it's not a nice finish for them."