I disagree with thosenwho think that Regina is not angry with her mother for killing Daniel. She(Regina) didn’t exactly seem happy with her (Cora) atthe end of the episode.
Also, people keep pointing out that Snow was manipulated into telling the secret. That is true, but Regina doesn’t know that. For all Regina knows, Snow searched out Cora in order to tell her. Regina knows her mother is manipulative, but she does not know that Cora manipulated Snow into telling the secret, only that she is capable of doing so. Regina did not know Snow well enough to know that she would try to keep the secret and after this point her opinion of Snow is already prejudiced.
I hope this makes as much sense in writing as it does in my head. 🙂