I.iii.60-74
Best
[CLEOPATRA Though age from folly could not give me freedom, It does from childishness. Can Fulvia die?] ANTONY She’s dead, my queen. Look here, and at thy sovereign leisure read The garboils she awaked. At the last, best, See when and where she died. CLEOPATRA O, most false love! Where be the sacred vials thou shouldst fill With sorrowful water? Now I see, I see, In Fulvia’s death, how mine received shall be. ANTONY Quarrel no more, but be prepared to know The purposes I bear; which are or cease As you shall give th’advice. By the fire That quickens Nilus’ slime, I go from hence Thy soldier, servant, making peace or war As thou affects. CLEOPATRA Cut my lace, Charmian, come! But let it be; I am quickly ill and well; So Antony loves.
Antony shows Cleopatra the detailed letter the third1 messenger gave him in the previous scene (and whose main points have been summarized before). That letter ends with the report of Fulvia’s death. I don’t think Antony’s word best here can mean that this is good news, as some commentators have imagined, nor indeed that he thinks Cleopatra will take it as good news. She is already free from childishness, and while the word may be an apostrophe to her (she’s the best!), I think it is a continued acknowledgement of Fulvia’s own greatness, Fulvia at her dramatic best, her most courageous and impressive, in her last moments, as would befit a tragic character. (To go slightly farther, I think this is an example of the Empsonian ambiguity that merges two possible interpretations. Cleopatra is best at understanding what Antony understands: that this is Fulvia at her greatest and her best.)
Accusing him, lamenting his “false love” for Fulvia, Cleopatra sustains the mode she’d entered the scene in, when she’d complained about Antony’s “mouth-made vows / Which break themselves in swearing”. She doesn’t take his failure to mourn sufficiently for Fulvia as a tribute to her, but as an aspect of his character. This is, of course, part of her mockery, and her character is such that her teasing can coexist with her seriousness, and she can teasingly complain of Antony’s failure to mourn Fulvia enough as predicting what his reaction to her own actual death will be. This might look like a narcissistic demand: Fulvia is dead and she’s thinking about herself. But it’s actually the opposite: the point is to rebuke Antony for his relative indifference to Fulvia, while it is Cleopatra who feels for her rival and counterpart.
Her prediction here about how Antony will respond when she dies is also important as setting up one of the climactic scenes in Act IV, when she will ask for a description of how Antony receives the mendacious report that she has killed herself: “Hence, Mardian, / And bring me how he takes my death” (IV.xiii.9-10). He won’t, of course, take the news as he takes that of Fulvia’s death, as Cleopatra realizes a little too late:
DIOMEDES She sent you word she was dead;
But fearing since how it might work, hath sent
Me to proclaim the truth, and I am come,
I dread, too late. (IV.iv.126-129)
Back to scene I.iii: Antony’s response to her is quite different from his earlier determination that he must break off from her or lose himself in dotage. His respect for her is suddenly serious. “Quarrel no more” sounds like a rebuke but that’s not quite right: he knows that she’ll be serious too, that her quarreling and chiding doesn’t show some failure to measure up to the situation. If he asks her to she will, and she does. The curl-tossing “Cut my lace, Charmian, come!”2 is there only to contrast with her immediate “But let it be”. She and Antony are in tune again. The rapidity with which this always happens will be, I think, the deepest motif of the play.
Depending how you count!
Fun to note the anachronistic clothing she’s wearing.

