The 6-1 hammering equalled the Hoops' heaviest ever Euro defeat and has sparked a bout of soul searching among Neil Lennon's Bhoys.
The defender reckons that Celtic may have taken a misguided confidence into the game following their impressive performances against the Spanish giants in their last three Champions League meetings.
Now Matthews, who was one of a couple of players to receive praise from boss Neil Lennon after returning from a long-term injury, says it is imperative that Celts make the most of home comforts against Hibs at Parkhead this afternoon.
The Celtic star said: "The players knew after the game that we had let ourselves down and we had let the club down. The manager didn't need to say anything but he was right.
"We didn't do ourselves justice, we let ourselves down. I don't know what it was but we were well off it and Barca were on top form.
"We were just so open that every time they went forward they looked like they would score. That was probably our worst defeat as a group and it hurt."
Matthews continued: "In three out of the four games we have played against Barca we have shown we can compete with them but on Wednesday we were just too open.
"In the three games we have had with them before, we tried to turn them and go long.
"Maybe the results we have had against them in these games gave us a false confidence.
"With the players they have you can't afford to do that, especially in the Nou Camp. So we were well below par and when you have players like Neymar at the top of his game you will get punished.
"But Real Madrid went there and lost five goals two seasons back so it is no disgrace."
It is clear the modest Matthews took scant consolation from the words of praise he was afforded by Lennon.
He said: "It is a team game and to be honest I didn't think I did play that well. So although it was nice to be singled out by the manager I didn't think I did that well.
"I was pretty sore for the next couple of days, as I haven't kicked a ball for nearly three months, but it is fine now.
"On a personal note it was just great to be back out and playing."
Matthews is adamant Celtic will learn from their Barca beating in Europe next term.
He said: "We knew at the start that it was going to be a difficult group and I would say that in four of the six games we did compete, but maybe we ran out of steam a bit at the end.
"The new lads who have come in were always going to take a bit of time to adjust to the way we play, but the more games they get the better they will adjust.
"I'm sure by next year they will have improved and we will compete.
"It is good that we have the Hibs game so quickly and we get the chance to put the Barca game behind us."