To underscore the excellent answer above, the scene in which the Nurse discovers Juliet "dead" is very telling of the natures of her and of Lord Capulet. In Scene 5 of Act IV, the Nurse enters and finds that she cannot rouse Juliet. She exclaims,
Alas, alas! Help, help! My lady's dead!
Oh, welladay that ever I was born!....
Oh, lamentable day!....
Oh me, oh me! My child, my only life.
Revive, look up, or I will die with thee. (IV,v,15-22)
When Lord Capulet enters, he claims that Death
...hath ta'en her hence to make me wail,
Ties up my tongue and will not let me speak....
Death is my heir, I will die,
And leave him all--life, living, all is Death's....
O child!...My soul, and not my child!
Dead art thou! Alack, my child is dead,
And with my child my joys are buried. (IV, v,37-67)
So, while both the Nurse and Lord Capulet cry that they, too, will die, Lord Capulet demonstrates more selfishness in his laments, stating that his joys will now be gone as Juliet has died. He thinks of his lineage and how the wedding will now turn to a funeral: "Our wedding cheer to a sad burial feast." All the sentiments of Lord Capulet contain his own reflection in them.
On the other hand, the Nurse simply expresses her deep sorrow and dismay, wishing herself dead if she no longer can be with Juliet. She thinks of nothing else, only "her child."