I just wanted to give you a big hug. I am in a similar situation right now. I had my 12 week ultrasound last week and the baby had a 3.8 measurement for the nuchal fold and I have a 1 in 60 chance of Downs.
However, because the baby is measuring ahead of dates, they wouldn't let me have a CVS and I have to wait for an amnio. This will be next Wednesday so I still have another whole week to wait - and then another wait for the actual results. I alternate between being terrified and thinking that everything will be okay and trying not to cry hysterically.
Allow yourself a good cry and then keep busy as much as possible - keeping busy is the only way I find that I am coping okay. I couldn't help myself and have had a look on the computer and I have actually found lots of happy endings...yes, even with nuchal fold readings as high as 6. I believe that one is actually here on BB. Knowing that there are lots of positive outcomes has helped me enormously...it reminds me that the nuchal fold is only a measurement, not a diagnosis and there is still a good chance that the baby is fine.
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