I am very unhappy about this -- I really don't understand how anyone can put blame on Sarah for what happened with Dana. In my opinion, she did what she had to, and was able to, do. Dana's friends, like Raidah, were ignoring how badly Dana was doing; and thus not really acting like friends.
I don't like Raidah because she acted so shittily towards both Sarah and, indirectly, Dana, and I wish she wasn't at the party. Kind of shitty of Jacob to bring her without asking beforehand -- at which point it would have become clear that neither Joyce nor Sarah would want Raidah there.
I guess maybe this is a setup for Raidah showing that she's changed for the better and apologising? I certainly hope so.