What can I do to calm my nerves about having an amniocentesis?

I am 22 weeks, and having an amniocentesis in two days. I think I've read too much on it and usually it always seems like the information is the worst possible scenario. They are concerned about spina bifida, and at first I was going to skip the amnio, but I feel it is best to be prepared especially since if there is something wrong with the baby's spine, its best for him to not be delivered lly as it can cause further damage. My ultrasounds all came back normal, but it was that stupid afp screening that came back borderline abnormal. And so I had this option of doing and so amnio was the next available test. Im so scared. I don't think anything is wrong with my baby, but if there is I want to be prepared for his arrival. How can I calm down?