Why are Juliet and the nurse important characters in Act 3, Scene 2?

Juliet and her nurse are important characters in this scene, in part, because they are the only characters to appear in it.  In this scene, we witness the nurse tell Juliet that her brand new husband has just slain her cousin, Tybalt.  The audience also witnesses some of Juliet's internal conflict now as well: she refers to her kinsman and her husband as "My dearest cousin, and my dearer lord," respectively (3.2.72).  When the nurse speaks well of Tybalt and curses Romeo, Juliet stops and chastises her.  Juliet is truly confused about how she is supposed to feel and how she can go about actually reconciling her conflicting feelings about her husband.  On the one hand, she should love and honor her husband; on the other hand, she should hate the man who murdered her kinsman.  Juliet uses a number of oxymora to describe Romeo at this point: "Beautiful tyrant, fiend angelical; / Dove-feathered raven, wolfish-ravening lamb! / [....] / A damned saint, an honorable villain" (3.2.81-85).  These mash-ups of good and bad things helps to indicate her level of inner conflict and turmoil.