"I have been altruistic for seven months, trying to hide the sadness of being in a situation I was not accustomed to," said the former Chelsea striker.
"My teammates are not to blame and it would be wrong of me to behave in a way that could disturb them.
"The squad and the fans all do everything they can to make me feel loved, but it is not easy to always wear a mask. I have to confess I am not happy, there is no point hiding it."
Although the Argentine sustained an injury during the summer, he assures that is not the reason for his absence.
"It can be convenient for some to bring out the story of the injury, but it simply isn't true. I hurt myself in July during the Copa America and now I feel fine.
"Considering last season as well, I did not expect to have so little playing time. I thought I would play more and be even more involved in the squad.
"A striker needs confidence, to feel important and Mancini is the first to admit I have been the most penalised."
Following the Livorno match, Mancio did comment on Crespo's campaign, but tried to put the blame on physical problems.
"Crespo has been the most penalised of all by injuries this season," said the Coach. "He needs to improve and he knows that, but he was on the field for almost the whole game and that is important. We know at the right moment, he'll be ready."
However, that is not an approach that sits well with Crespo, who responded sarcastically to these statements.
"Mancini said I'd be there when it matters? If he says so%uFFFD All I know is that I don't think of myself as a player reserved only for the Champions League, but also Serie A.
"I hit my record today - a whole 85 minutes! Shame we're in February already%uFFFD"