Askey was left angered after watching his side capitulate in the second half having let two leads slip over the course of the game.
Pools went in front when Joe Grey headed in early in the first half in a game they, largely, dominated for around an hour – albeit Olly Sanderson was able to level the scores soon after the half hour when converting well at the near post.
But Hartlepool soon restored their lead thanks to a terrific strike from Callum Cooke who curled into the top corner.
From that point on Pools ought to have gone on to win the game but saw things collapse inside seven second half minutes.
Canice Carroll headed in after Pools were unable to clear their lines from a free kick before Josh Ashby put Oxford in front almost immediately from the kick-off after the home side capitalised on a cheap turnover in possession.
And the Hoops capped a stunning turnaround when substitute Pierre Fonkeu was handed a clear run on goal after Emmanuel Onariase’s untimely slip.
Fonkeu finished well underneath Pete Jameson before adding a fifth for the hosts five minutes from time when turning in a rebound from another set piece.
Askey was left to deal with the frustrations of those who had travelled before conceding they had let both themselves and the club down in such a defeat, with the lack of a response after falling behind a particular worry.
"It’s really difficult to explain it,” Askey told BBC Radio Tees.
"We should go in at half-time two or three up then in the second half we talked about keeping it going, what we’d been doing, and then for some reason we never went forward.
"I think the two mistakes killed us. Luke [Hendrie] trying to dribble out of defence and then Mani [Onariase] slipping. And then I don’t think we could believe that we were two goals down.
"But the manner in which we allowed the rest of the game go on wasn’t good enough and they’ve let themselves down. They’ve let the club down.”
He added: "One thing I expect is for people to dig in and work hard and close people down, no matter what the score.
"It looked as though too many gave in again. There was the odd one or two who had a go but that’s all it was and you can’t accept that.”
Despite such a desperate defeat for the club, Askey was keen to move on by suggesting they remain in a decent position with five wins from their opening eight games of the season – with this defeat hopefully being a turning point for his side.
He said: "All we can do now is have a look at it. It’s gone. We need to learn from it if we can possibly learn from it, or I’ll learn from it, and we’ve got to roll our sleeves up.
"We’re still in a decent position and hopefully that’s a bit of a watershed moment and it doesn’t happen again.”