The Blaugrana have already sealed a second consecutive Primera Division crown, but Busquets acknowledged that their historic reverse at Anfield had left a deep wound.
“We knew we had to play today, but it was really difficult for everyone,” the midfielder told the media in Spain.
“We wanted to be at 100 percent but it was a struggle because of what happened [at Liverpool].
“We have to keep going and we have to focus on the Copa del Rey final. Hopefully the wound which the club the players and the fans have will heal.
“The challenge ahead isn’t a small one, either. The double’s no small thing but the wound from Liverpool is deep. We have to keep going and hopefully those that are injured recover quickly.”
The injuries across Barcelona’s front line got worse, not better, on Sunday as Philippe Coutinho was added to the list.
He was substituted in the second half and the club have confirmed he’ll miss about ten days.
Victory there would help start the healing process, but consecutive humiliations for Barca in the latter stages of Europe’s premier club competiton have angered fans at Camp Nou.
Allowing Liverpool to come back from a 3-0 first leg deficit this year only compounds what happened against Roma last campaign.
The Italian club dumped Barca out at the quarter-final stage in 2018, overcoming a 4-1 first-leg defeat to win 3-0 at home and advance on away goals.
The Catalan fans whistled the players today and Busquets said he understood their frustration, before commending their loyalty.
He said: “We have to be grateful to the fans. It seems that we’re not living in this world at times but we are. We know how fans are feeling but their behaviour has been spectacular.
“They showed their disappointment at first, but after that they were 10 out of 10. We’re all p*ssed off, but we have to keep going. There’s nothing else for it.”