The Invicta Virtuosi driver contracted a broken wing before spinning out at Massenet while running in fourth, hitting the wall before his car burst into flames and prompted a red flag.
Zane Maloney, who had been running behind him for Rodin Carlin, had a near-miss but took evasive action.
Speaking after the race, the Alpine Academy member said he initially thought he had gotten away with his contact with the wall at Swimming Pool, hence not pitting immediately after.
He told Motorsport.com: "I just made a mistake, clearly, to be honest. I don't really remember it 100% but I know that I went into the wall here, then exited the second part of Swimming Pool and I felt that I just did the front right.
"I went to the last few turns and went on the main straight. I tried to weave and I thought maybe I'd gotten away with it, and went through turn one and it was all normal, but clearly I hadn't.
"And yeah, when I got to the top of Massenet, as soon as I had the car loaded, it just completely went on me."
Doohan, son of motorcycle racing legend Mick Doohan, said the fact the whole car caught fire was "very worrying" and initially thought it was just the brakes which had caught fire.
He also said he was "definitely a bit groggy for a while" after the crash and was "very fortunate" to escape in time, adding: "Initially, I couldn't get my buckle loose.
Heartbreak in Monaco as Jack Doohan's race takes a sudden turn 💔#MonacoGP #F2 pic.twitter.com/d7YOXStijZ
— Formula 2 (@Formula2) May 28, 2023
"Luckily, to be honest, I was probably out of the car in 0.2 of a second, very quickly. But yeah, if I couldn't have got out of the car, it could have been quite scary."
Doohan has had a difficult F2 season so far this year, and currently sits 13th in the standings after five rounds with 28 points. This time last year, he was sixth, with 45 points.
He was frustrated by crashing out as it was "the first weekend where we've had a competitive car again and potentially could have been shaping up to a nice race."
The Australian said: "Potentially just trying to push too hard to catch for what I've unfortunately lost that's been out of my control. And yeah, I've learned that the hard way.
"I wish I didn't have to because I'm just trying to go for too many points. But hey, that is how it is now so gonna make up for it now going forward."
He added: "It's unfortunate because if I would have had a normal season, I would have been frustrated with the result but I would have already had a good base of points behind me. So that makes it a little bit more frustrating.
"Hopefully we can salvage what is still available [of the car]. And then I feel for the boys as well, a lot of work to do in a short turnover time. But as long as we can get it all on track for Barcelona, I know we'll be quick there."
