"Dear slow Montague, they call Romeo,
I am appalled by your behavior,
to show up to a Capulet’s party, uninvited.
I would have brawled thee,
If not, my uncle’s word had been heard and save thee.
Thou art a wenching eye-offending modwrap.
Where wast thou when our beloved prince waived us to put up our swords?
Was thou blenching in the bushes, as a coward would?
I, Tybalt of the Capulet house, thirst to challenge
thee, Romeo, to a duel to the death.
If thou shall not except then thou is a coward of the worst kind.
If thou shalt except, prepare to breathe your last breath.
The death march is near, dear Romeo,
so, live in fear Tybalt of the Capulet house."
Is the poem above an English sonnet that follows the rhyme scheme ABABCDCDEFEFGG? If not, why?
It doesn't quite fit the bill yet. First, all lines must be iambic pentameter; that is, they must predominantly be composed of iambic feet (a beat that sounds like a heartbeat, like a-LONE or good-BYE), and have five of those per line. Thus, the line "to show up to a Capulet’s party, uninvited" is too long, having 7 iambic feet instead of five.
Second, you only have properly rhymed two of the lines (death / breath). The rest are all unrhymed, which means the ABABCDCDEFEFGG criteria has not been met.
Another normal expectation of English sonnets is that there is a "turn" at the last couplet (the GG part). A "turn" is where the ideas expressed thus far are suddenly shown in a different light, a twist, if you will, as in Shakespeare's Sonnet 130.