"Betrayal" isn't game changing episode, but it's an interesting one in comparison to the previous episodes. Victoria Grayson has been positioned as the final boss for Emily, the last person Emily will take down. Indeed, Victoria has been the queen bee with all the power and influence to pull strings and get David tossed in prison.
This episode, however, turns that around. We see Victoria in the past actually trying to save David by talking to the prosecutor, Kingsly, and changing her testimony. Then, the episodes ends with the implication that she was the one who sent the emails, not Emily, and a flashback showing David giving her earrings which she still has in present day. In fact, Victoria is much like Emily, trying to make up for past wrongdoings. Whether Victoria was the actual person who sent the email isn't confirmed, the editing seemed to indicate that, and I like that twist a lot.
Once again, I'm not sure why Declan and Jack are in the show. There is drama, all right, but on the peripheries of the most important story, Emily's revenge. We still haven't seen why they are important to Emily or the end game.