The guy controlled the ball with his hand so the ref gave handball. Some they give and some they don't.
Barca were poor and got what they deserved. 60 mins against 10 men and the keeper had no more than 2 or 3 saves to make. Not good enough from 'the best team in Europe'.
As for the ref - I think the only big decision he got wrong was the sending off. The Barca guy knew exactly what he was doing and even had a sly look through his fingers to make sure the ref had seen it.