The passing grade varies every year.
I found the exam very difficult to write. It was long (about 2.5 hours for the first half, and 3 hours for the second) and I found that the more I wrote, the more confidence I lost. I left that exam feeling like there was a good possibility that I failed... BUT I passed, and so did everyone else in my nursing class.
I think the most important thing to do when preparing for the CRNE, is to increase your confidence by any means possible. I personally found studying a lot to be helpful. I asked the nurses who wrote last year what they remembered about it, and I studied that. (by the way, study the major illnesses that you find on a medical unit - liver disease, kidney failure, hypertention, diabetes, and know the cardiac markers).
A lot of people don't like the CNA prep-guide, but I personally found it helpful because it made me feel like I knew what to expect, and that made me feel more confident.
You'll probably be fine, but good luck anyway!