I think she was partly sincere. I think she forgot what she had said about Helen. It appeared to me that that was the comment that shook her the most when Julie read them to her. I think she doesn't care one whit about Candice or what she said to her, other than perhaps how it makes her look, but, IMO she was sincerely apologizing to Helen. It made her nervous to say it, at the very least, because her voice was a bit shaky, just like after Julie told her about herself on her elimination night.