To me, this depends on how you see the nurse and how you think that she feels about Juliet.
If you think that she truly loves Juliet, then this scene shows her stricken with grief. She's so sad, you can say, that she is barely coherent. She keeps repeating herself over and over again. Here is an example of how she does that:
O woe! O woeful, woeful, woeful day!
Most lamentable day, most woeful day
That ever ever I did yet behold!
O day! O day! O day! O hateful day!(55)
Never was seen so black a day as this.
O woeful day! O woeful day!
But what if you think that she doesn't love Juliet that much? What if you are sort of cynical? In that case, you can look at these words and say that she is just faking it. You can say that she does not really care -- she's just saying stuff over and over without really meaning it. If she meant it, wouldn't she say why she's sad? Wouldn't she say something to tell us what she if feeling other than "this is really terrible?"
So I think it's up to you and to your own ideas about her true feelings for Juliet.
It shows an audience how much Nurse loved Juliet. Juliet was practically Nurse's own daughter!! Nurse had even mentioned this at the beginning of the play. One major idea that relates to this question, is how horrible the relationship between Juliet and her parents was. Juliet barely even knew her parents, and vice-versa. Nurse really filled in as that role for Juliet, and really provided her with the love that a child should be getting from his/her parents. When Juliet was found "dead" (the first time), Nurse was absolutely heart-broken. For her, it was like losing a child. Of course Juliet's real parents were sad, however you'll notice that they really didn't carry on too much with it as Nurse did, or even as much as Lady Montague did when she found out that Romeo was dead. Remember, Lady Montague went as far as committing suicide herself.