The former Barca coach passed away on Friday after losing his long battle against cancer and the 3-2 victory was the Catalans' first game since his death.
"Sunday's match against Villarreal was very difficult because it is hard to stop thinking about events that happened together with Tito," Busquets said at a press conference.
"It was very important for us to win an emotional game like the one versus Villarreal."
The Spain international then went on to discuss Atletico Madrid's Champions League semi-final win over Chelsea and stressed that he was not surprised by Diego Simeone's side's achievement.
"It does not surprise that Atletico Madrid made it to the final of the Champions League.
"The fact that they have made it means that they deserve it."
Barcelona were beaten by Atletico in the quarter-finals of the competition.