Nightmare - 700 to 640 (all in verbal). What Should I do?

This is probably the worst thing that could happen to a re-taker.

I took my first GMAT in March, scored 700 (51q 32v). I decided to retake to try to reach the 80% 80% split. I went through e-gmat's online course. Did supplement prep problems and Verbal V2, around 75-80% accuracy.

Then I took the test for the second time today, 51q 25v. Very Very Disappointed. I was out of the zone. Spent 25 minutes on the first 10 questions - lost my pace, started scanning through reading comprehensions, and picking answers without a thorough error analysis. I knew I won't get a big increase in verbal, but I thought I would at least score around 34. I did contemplate about cancelling my score, but after spending 3.5 hours on the exam, you kind of want to see how you do. So, there goes the disappointment.

I know it's probably best to test again to proof that my ability is more close to the 700 range, but I am so tired and sick of GMAT that I just want to toss it out of the window.

What are the disadvantages if I don't retake? (I can already list quite a few myself). Desperately need advice!