BIG case of cold feet, and perfectly normal!! I know of couples who bickered right up to the day of, and once it was all over and done with, sat back and laughed at how overly-sensitive they were about the other. You've already made the biggest decision in life, and that was having two children with your FI. Because of your children, you will be a part of each other's lives forever, so you see, you're stuck with him already (lol) and therefore there isn't much more to be afraid of now is there?