Somehow, after over one hundred and forty years of searching for her, missing her, wondering where she was, hoping she was alive, and obsessively thinking about her, Damon is still surprised when Katherine tells him it had always been Stefan. How could it have been Stefan when he remembers the way she was with him? How could she have always gone for Stefan when it was Damon who loved her, Damon who accepted her, Damon who searched for her?
And yet, she says the words and he feels broken inside. Like the part of him that held him together since he turned has just been ripped out. Like the earth stopped moving, turned upside down, and started spinning backwards.
But the really sick part, the part he can't get over, is that he still loves her. Oh, he hates her too—hates her for not being straight with him, hates her for letting him believe she was in the tomb, hates her for doing this to him—but just because he hates her doesn't mean the one hundred and forty five years of love and quasi-worship just disappear. All that talk of a magical switch to get rid of emotion? Yeah, doesn't really exist.
He wanted so badly for her to just tell him she loved him, wanted to just forget everything and fuck her until the sun came up (or longer, if he was up to it). And he almost wishes he hadn't asked the question, thinks it would have been nice if she'd of let him live in his make believe world for a few more hours. Just to fuck her and hold her and kiss her one more time before she ripped out his heart (figuratively, of course, for he thinks it is still there somewhere).
He thinks it's ironic that the one time she doesn't lie is the one time he'd rather of heard a lie.