Once Mincing departs, Millamant angrily responds that Mirabell’s love for her is no more a secret than it is a secret that Marwood revealed his love for her to Wishfort because Marwood is in love with Mirabell herself. Mrs. Marwood retorts that Millamant is upset and should calm down before she breaks another fan.
Once Mincing leaves, the argument takes a nasty turn. Millamant is openly angry and tries to strike Marwood in a soft spot, her love for Mirabell. But Marwood, perhaps because she knows the details of Mirabell’s plot, is much calmer and so has a much cleverer response. Millamant’s anger reveals her actual love for Mirabell.
Millamant laughs in Marwood’s face, and claims that Mirabell’s love for her, which she seems not to care about, has made him so upset and morose. She tries to convince Marwood that she isn’t encouraging Mirabell’s love because she doesn’t care about him, but Marwood doesn’t believe her. Marwood tells Millamant to tell Mirabell that she hates him.
Millamant usually laughs when she’s uncomfortable or has nothing clever to say and so chooses to seem mean instead. Here it is both these reasons that cause her to laugh in Marwood’s face. The laughter doesn’t seem to bother Marwood much, though.
Again, Millamant laughs at Marwood, commenting that she’s surprised that Mirabell loves her, Millamant, when Marwood is as beautiful and as young as she. Marwood threatens that Millamant’s happiness will run out sooner than she thinks.
Millamant’s comment that Marwood is just as young and beautiful as Millamant suggests that beauty and youth alone are not enough to create love. Notably, this is the opposite of what Millamant argued to Mirabell in Act 2, Scene 6. Perhaps Millamant is realizing that Marwood’s cruelty is what makes her uninteresting to Mirabell, and therefore Millamant’s own attempts at cruelty are misguided.