"Villain and he be many miles asunder!
God pardon him! I do with all my heart."
I have placed a (!) at the end of the first line; for Juliet is evidently speaking here in the ambiguous manner of her subsequent speeches. She means an indicative, but wishes her mother to understand her in the optative mood. The editors of the last century, not understanding this, have without any authority changed 'be' to are. In the next line him was added in the 2nd folio. I should be inclined to make an Aside of 'I do with all my heart,' as she pretends to plan his death. In the Globe Shakespeare the first line is made an Aside.
"My poor heart is so for a kinsman vex'd."
Both 4tos and folio—followed by all the editors—read 'Is my poor heart,' connecting it with the preceding 'dead.' It is manifest they did not understand the ambiguous language of Juliet.
"To wreak the love I bore my cousin Tybalt."
The necessary addition was made in the 2nd folio.