The definition for paradoxical phrases in this context would be that they are statements that seem contradictory or logically unsound at face value but make sense on careful investigation.
In the lines just before, Juliet's mother has told her about Romeo's villainy in that he has killed her cousin Tybalt. Juliet responds, in part, by saying:
Indeed, I never shall be satisfied
With Romeo till I behold him—dead—
Is my poor heart, so for a kinsman vexed.O, how my heart abhors
To hear him named and cannot come to him
To wreak the love I bore my cousin
Upon his body that hath slaughtered him.
Let me be ta’en; let me be put to death.
I am content, so thou wilt have it so . . .. . . Come death and welcome.
I long to die
If what thou speak’st speak not of remedy.