[Had she been thinking better, she might have privated the conversation. But Rebekah is often blinded by her emotions and makes careless mistakes like that because of them.
It doesn't really matter though, in the long run. It saves her the explanation to why she's angry.]
Were you ever going to tell me the truth? [She knows the answer. Of course not. He's a liar and a coward.]
That you saved her over me? [His sister. You chose to save some baby vampire over your family.]