Now that everything has become clear to Hanekawa, there's only one thing for it to resolve the current situation... it's time to write a letter.
With no direct way of talking to her own Black Hanekawa alter ego, Tsubasa instead pens a long missive to her counterpart, explaining what she's realised about the existence of Kato - effectively another apparition created from herself, one created to alleviate her envy and other negative emotions - and imploring Black Hanekawa to stop it from doing any more damage and to bring it home where these feelings can become part of Hanekawa herself once again.
Of course, this is easier said than done, and by the time Black Hanekawa has made her way to find Kato he's all set to burn down Senjougahara's apartment. Despite her best efforts, it seems that Black Hanekawa can do nothing more than stall this other part of her master's personality... but then again, maybe stalling is all that's required when a certain hero is on his way back to save the day. Thus, Kato is incapacitated, Hanekawa can finally find some kind of closure with regard to her feelings for Araragi, and another apparition has been dealt with while also allowing its master to move on and learn a little more about her own life, expectations and needs.
If Monogatari Second Season so far has been wonderful (and make no mistake, it has), then this denouement to its first story arc is downright perfect. The visuals which accompanied Hanekawa's letter to her apparition of an alter-ego is one of the greatest things I've seen in television anime (and I only exaggerate slightly), and Hanekawa's meeting with Araragi quite literally reduced me to tears with its bittersweet beauty as one of the most heartfelt scenes I've witnessed in quite a long time. It's the ability of this series to leverage its strong characters to elicit whatever emotions are required that made me fall in love with Bakemonogatari, but this particular episode might well be the natural pinnacle of its craft - my biggest worry for the rest of the series is: how can it possibly top this?