PSG carried a 4-0 first-leg advantage with them to Camp Nou but suffered a crushing loss that saw them concede three goals from the 88th minute onwards.
It was a shambolic display from the Parc des Princes side, according to Japan boss Halilhodzic, and one that threatens to leave a significant scar.
“This defeat will not only leave a mark on PSG this season, it is a trauma that will not heal so easy and will haunt future PSG's generations,” he said to Goal. “They need to unite quickly, players, coaches and board - everyone must invest a big effort to keep focused on Ligue 1 title race.
“It is hard for me to understand what happened at Camp Nou. Maybe PSG were not prepared psychologically, maybe they were over-confident and maybe they feared a debacle. But believe me, there players will never forget this defeat!”
The outcome of the tie seemed decided when PSG ran out four-goal winners – a deficit that had never previously been turned around in a knock Champions League tie. Halilhodzic believes it was a dreadful collapse for PSG, with a tactically naïve display combined with poor refereeing leading to an embarrassing exit.
“In first leg I was shocked how poor Barcelona looked, I couldn't believe a team with such players, including Lionel Messi, the best in history, could play so badly,” he said. “Marco Verratti, Adrien Rabiot and Blaise Matuidi totally outplayed them in midfield and if Edinson Cavani, Angel Di Maria and Julian Draxler had been more accurate, it could have ended worse for Barca.
“But in the second leg Barcelona took a risk with three defenders, PSG were naive and we must mention the referees too.
“PSG shouldn't have lost so heavily, but it remains questionable whether the referee would awarded those two penalties to a smaller club. I don't think so - especially the one on Suarez, which came from situation that we see a million times in one match.
“There was also the Javier Mascherano situation, and even Gerard Pique could have been awarded a red card for a foul on Cavani. All the dubious decisions went Barcelona's way."
“PSG were tactically a disaster! No aggressiveness, no possession, no passing - they were intimidated, had no midfield, no rhythm, no fight... I understand Verratti and Rabiot are young players but they had to do much better.
“Yes, they have the right to be mad at referee, but most of all they have to blame themselves. Especially defensively, they were catastrophic!”
To this end, the coach pointed his finger at one player in particular.
“Thiago Silva was not at a captain's level,” he said. “He is one of most experienced players in the team - he had to be the one to shout, do something, make some foul, anything to lift his team when things got bad. To affect other players with his confidence, to calm them in dying minutes. And to me he seemed lost!”