I know how you are feeling, I took a few CAT tests before taking the actual GMAT and I scored alot lower. I'm not going to say my score because its quite embarrassing.
But I do relate my performance was due to the anxiety that I got on the test of the day.
But I just retook the test, I made sure that I didnt review any material a day before and I went to bed early. The following day, I made sure that when the anxiety kick in during the test, I took a deep breath, relaxed and refocused. I did much better than the first time, the score was 200 points better. Its not the score that I want but I know my score reflected what I put in and believe me I didnt study enough.
But in my opinion, I think the best thing you can tell yourself is not to give up....if you need a break for a week, go for it. However, I don't suggest taking a long break because you might forget some material. Or what you can do is during that break just review 5 mins here and 5 mins there so you dont forget and once you are ready you can study harder!