Some people might not believe me when I say this, but I'm going to say it anyway.
Elena loves Damon. She does. I thought she did in 2x22, but I feel más sure now. Just don't expect her to admit it for a while yet.
It's not so much what she says in 3x12, as what she DOESN'T say. I know that's a bit weird, but oso, oso de with me.
The first half of Season 3 was about the evolution of DE's relationship, the closeness between them that developed and grew. The intimacy they shared (like Elena getting into cama and falling asleep siguiente to Damon), the sparks that flew (think of 3x06, the training room scene), the mutual trust and reliance on each other for support in dark times. But now he's kissed her, she's reached a cross-roads emotionally. All the feelings she had for him she always kept under wraps for the greater good are in danger of brimming over.
In an interview (I think it was with TVGuide), Julie Plec dicho of 3x11:

"She says to Matt, how did I become the kind of girl who loves vampires...and she says vampires, not A vampire, and I think that's very telling; because it's kind of the first time she's referred to the 2 of them on the same level as opposed to being in amor with Stefan and being angry at Damon. And her relationship with Damon has evolved so much over the course of the season that I do think those feelings are there and she doesn't know what to do with them."

The latter part of the quote above is worth special attention. Julie doesn't say Elena doesn't know what her feelings are, she says she has feelings but she doesn't know what to do with them.
I think anyone who falls in amor with somebody they think they shouldn't goes through a lot of turmoil and angst in the beginning. Even acknowledging the truth of what they feel is very painful. They may feel guilty. They feel confused. They struggle to accept the depth of their feelings because they don't think they should have them. So they try to deny that those feelings are there, o they ignore them o pretend they don't have them because that's easier than admitting the truth. Elena prevents Damon from joining her and Bonnie's road trip using Bonnie's reunion with her mother as an excuse. But the real reason isn't Bonnie's mum (notice that Bonnie doesn't raise any objections), it's Elena. Being so close to Damon for most of the día means she can't avoid the conflicting emotions that are constantly surfacing in her heart. If she's stuck in a car with Damon, and if she spends the día with him, then no way will it allow her some time and el espacio away from all the issues she doesn't want to face. Bottom line: Elena's scared. She doesn't mostrar it. But she is. She's afraid of what she feels for Damon, and of the sequence of events that might unfold should she decide to act on her feelings. When Bonnie asks her about the kiss, Elena refuses to go into details. She doesn't dissect the kiss. She doesn't fob it off por saying something off-hand, like "He kissed me, it wasn't a big deal," o "He kissed me, but it didn't mean anything," o even "He's a good kisser, but tu know I'm a hundred percent devoted to Stefan." "It doesn't matter," she says when Bonnie asks her if the kiss was good. Clearly, it does matter, because if it didn't, then she wouldn't have to act so hard as if the kiss didn't mean anything to her.

Something huge that we can take away from this episode is that Elena doesn't feel guilty about besar Damon. And that means that when they kissed, it felt RIGHT. If she was deeply in amor with Stefan and remained a hundred percent committed to him, she would have felt as though she'd cheated on him and and be wracked with guilt about the kiss because she'd felt she'd done wrong, but she's not. por admitting to Stefan that "I kissed Damon", she is holding herself accountable, almost making it sound as if she was the one who initiated the kiss even though she didn't. And you've got to wonder the deliberate choice of words here, when before, she was telling Bonnie "DAMON kissed me."
Some people are speculating that Elena is trying to make Stefan jealous, but I disagree. If she'd wanted to make Stefan jealous, she could have kissed Damon many times before this. Katherine would have used Damon to make Stefan jealous, but Elena wouldn't. Her relationship with Damon is simply too precious to her to misuse it like that.

I suspect that Elena has a long hard road ahead of her before she is ready to admit how she really feels about Damon. It will be a road littered with much pain, angst and heart-break. Sometimes, it takes something fairly dramatic o earth-shattering before a person who is in deep denial about their amor for someone is willing to do something about it. It could well be the case for Elena. It might take almost losing Damon before she's finally able to admit that she loves him. We have to be patient with her. Falling in amor with someone who is off-limits is very scary. It's complicated. It hurts. You're essentially battling with your own heart. Elena is a loyal person, and if she does decide to give Stefan another chance, then I won't blame her. But her corazón no longer belongs to Stefan, and no matter how hard she tries to run away from the truth, it will always catch up with her in the end. Because as long as she denies what's in her heart, she is denying a part of herself.