Kristin has come inside info from Damon Lindelof, that she shared a couple of days ago here: Watch with Kristin - Spoiler Chat
"From Sandy in Oregon: On Lost, what will happen to Desmond after Charlie's death?
Excellent question! And I have the answer from the man who knows bestest—Damon Lindelof. He tells me, 'Desmond will have to deal with the aftereffects and the guilt of it. He will question whether or not Charlie would have made this sacrifice had he not told him that it was what he was going to do. He will question the role he played in Charlie’s death.' So, it sounds like big sexy Dezzie is haunted by Charlie's passing, as many of us fans are!"