Basically, the last tea party makes it obvious that Beato is in love with Battler, to the point of total self-sacrifice. The part where she thinks though a haze of agony, about how it would have been nice if that situation from the end of chapter three (meaning, Battler trusting her, and caring about her) had lasted longer, if she hadn't told him the truth, and then telling herself that wouldn't really have been "winning" is definitely BAWWW-worthy.

People are still basically stuck in harsh mode after the end of chapter three, and they're missing that Ange's story is outright said to be about "understanding witches". Ange herself has quite a measure of sympathy for Beato, even acknowledging they're both similar in their need for Battler. (Meaning, the implication is that Beato is both sympathetic and deeply, deeply lonely. Of course, that's obvious as far back as chapter two, with her strong reaction to Shannon's rant about the "sanctity of love".)

Basically, the entirety of the last tea party is Beato playing a role that causes herself both extreme physical and mental agony. Battler doesn't want to see a sympathetic opponent, he wants to see a "witch" to beat down and destroy. So that's what she becomes for him--a cackling, two-dimensional witch who taunts him cruelly to make him keep on going and "finish the job", even as she holds back her tears.

The character portrait work is amazing here, btw. For example, there is a moment in time when Battler calls her "MY Golden Witch", and Beato's "cackle cackle face" briefly turns into a normal teary one before going back to "cackle cackle". Just all around excellent.

And that very last sceeeeene. Bawwwwwwwwwwwwwwwwwwwwwwwwwwww.