Answer:
She thinks both Romeo and Tybalt killed each other
Explanation:
Juliet would obviously be confused since the Nurse can't really be clear:
<em>O Tybalt, Tybalt, the best friend I had! </em>
<em>O courteous Tybalt! honest gentleman! </em>
<em>That ever I should live to see thee dead! 1785
</em>
Juliet responds:
<em> What storm is this that blows so contrary? </em>
<em>Is Romeo slaughter'd, and is Tybalt dead? </em>
<em>My dear-loved cousin, and my dearer lord? </em>
<em>Then, dreadful trumpet, sound the general doom! </em>
<em>For who is living, if those two are gone?</em>
<em />
She seems to think that they both died fighting each other