Well if I'm reading this correctly, you did fdisk /dev/disk0 which formatted the entire disk, not /dev/disk0s# where # is the partition you wanted to format. If you still have Mac OS and your Windows partition on the Mac, you may just need to boot into the recovery partition and click repair on the disk, it will find the Windows partition and re-write the MBR.
If you can't boot either, then you'll need to reinstall Mac OS, then redo your bootcamp. Lesson learned, but it is never a good idea to adjust your partitions while using bootcamp.