Who said anything about that? I said, she had sex with him once. He compelled her, after, and yes, he abused her. My point is that we do not see anything sexual happen after the compulsion.

In the episode, it is dark when Caroline and Damon go home together. The next time we see them, it's morning, and he's kissing her implying that they had sex. He feeds on her, and the next time she wakes up she's scared, so she still hasn't been compelled. She tries to escape, he stops her, smells her blood and his face changes into a vampire face, implying that he's going to feed on her. There are no sexual implications. Caroline is happy when we see her after, so she's clearly been compelled, but there is still no sexual implication. She was compelled for vampire secrecy, and most likely to be used as a blood bag.

From that point forward, there is no sex between the two of them, that we see, at least. Assuming we actually see that, then I'd be right there with you, branding this as him raping Caroline. But we don't.

She tells him he abused her. Yes he did. He abused her, by verbally insulting her. By forcing her to do his bidding. By using her as a blood bag. Not sex.

Don't get me wrong, I despise Damon, but I always found this odd, because it's based off the assumption that after he compelled her, they were continuing to have sex. He clearly compelled her to use her to feed on.