Alright, after a couple of weeks where I was started to worry about the direction of the show (I thought "Crossfire" particularly felt like an episode from an entirely different, dramatically weaker show), this brought me back to remembering why I loved it in the first place.
Putting us in the same position as Carrie by not knowing who it actually was at the door displays how good the show can be with making a small twist so effective and uniquely terrifying without delving into the sensational (like, say, the explosion last week). And then yeah, the final shot was both impossible to bear and beautiful to watch.