The passage that explains Rosalie's feelings is in Chapter 7 "Unhappy Ending" of Eclipse. Rosalie describes her human life in 1933, when she was proud and shallow, engaged to a man of a high social class who was handsome. It was a shallow engagement, based on social status instead of love. After her fiancee raped her, she was left for dead, and Carlisle found her. As a vampire, Rosalie had her revenge.
She explains to Bella that she is jealous for several reasons, first, that Edward desired Bella, and not her. Even though Rosalie isn't in love with Edward, she couldn't imagine anyone not desiring her, because she is so beautiful. Second, she explains that she is envious of Bella because of her humanness, "Don't you see, Bella?...You already have everything. You have a whole life ahead of you -- everything I want. And you're going to throw it away. Can't you see that I'd trade everything I have to be you? You have the choice that I didn't have, and you're choosing wrong!" (Page 166).