You seem to be holding together quite well, which is unusual for someone breaking off a 6 year relationship, heh.
I honestly believe you are making the right decision if you feel that many regrets and worries. Better to abort while you still can, then either be stuck unhappy, or go through a divorce.
Make sure you know what you're doing before you act, but if you do, then more power to you. And you have my respect for being so objective of the situation.