Bartomeu said the Italians played better and deserved to progress to the semifinals.
It had appeared as though it would be a comfortable night for the Catalan side in Roma having had a 4-1 win at home.
But the Italians had other ideas and produced a superb performance to come out on top 3-0.
“They (Roma) dominated the game and they believed in themselves. When you believe, you push forward and these things happen,” Bartomeu said.
“They played better, I am not happy for the fans.
“We are sad but we congratulate Roma and their fans, we will need to analyse what happened, return to the league, the cup but today we are sad.
“The ties clearly affect you, we will need to analyse it and return forcibly because we have an important game against Valencia.
“I am sure that the players will recover even though it is a big disappointment,” he added.