Head coach Ariel Jacobs described the reality of overseeing Valenciennes' relegation from Ligue 1 as "a nightmare".
The north-east club's return to the second tier after eight seasons in the top flight was finally confirmed by Sunday night's home defeat to Bordeaux.
After Maor Melikson missed a first-half penalty, Julian Faubert's goal earned the visitors to the Stade du Hainaut a 1-0 victory and left Valenciennes nine points adrift in the relegation zone with only two games remaining.
Belgian boss Jacobs, who took charge at Valenciennes in October, told L'Equipe: "It's a nightmare.
"We had prepared for this eventuality since last week, even if it wasn't mathematically assured.
"But beforehand the players seemed resigned and beaten in the dressing room and so it wasn't an easy situation.
"We got what was coming to us and what we deserved, even if we did put up a fight.
"A real lack of spirit was, however, a key element."
Former Anderlecht boss Jacobs, 60, confirmed in February that his spell with Valenciennes would be his last before he retires from football.
But it remains to be seen whether or not the Vilvoorde-born coach decides to remain at the Hainaut and lead VA's bid to secure an immediate return from Ligue 2.