LittleBen, some good lessons in that break. If wood is sound it breaks along grain lines. If rotten, across grain. Your bow broke along a grain line so that grain configuration is apt to break again in the future. Catalog this so when you go for your next board you will pic one with less runoffs.
I built bows for years before I ever had one break(most just bent badley)...but when it did, it was spectacular! It was ERC and ended up in 10,000 pieces.
As long as you can learn something from this experience it is not a loss!