Sorry to hear about that!
It is very odd that you scored that much lower in quant section. I've heard of people scoring 2-3 points lower than their practice GMATPrep but to score 8+points lower? This is the first time!
Your verbal seems to be on a lower side as well. This does not surpise me as recently a lot of people have been reporting lower scores in GMAT verbal section compared to the verbal scores they saw in the practice tests. I suspect that Pearson has changed the scoring algorithm for verbal.
My suggestion would be to take a break, allow about a month or so for more GMAT prep, and take another test in July or so.
The truth is, it might have been your unlucky day. Don't let this score discourage you or lower your self-confidence.