Fear can be a powerful deterrent, but the trick is not to let it rule you. Start small, and convince yourself that cutting fabric was what that fabric was made for- you are not destroying it but transforming it into something beautiful.
If fear persists, then I would seek professional help- there is nothing wrong with seeking a counselor to help you deal with that fear that is stopping you from succeeding. Better to deal with it once than let it hinder you forever! :-)
Let us know how it's going.