You can order the outer panel. Its available at searspartsdirect.com for about $41. Just type in your model number and look under the "Door Assy" heading. To replace, just follow these steps:
You have to remove the inner door panel that goes around the perimeter of the glass. You can use a small screwdriver to carefully pry the plastic up and work
your way slowly around the perimiter of the glass. Most microwave ovens
also have grooves in the panel that you can insert the screwdriver into. Use care not to pry against the glass. The glass is tempered and also has an RF shield that prevents harmful microwaves
from potentially harming the consumer. If you break the glass, you will need to purchase a new door.
The door handle screws are located behind the inner panel. Remove the door handle and any screws that may be holding the outer panel in place. Some panels are simply snapped in place.
Remove the broken panel and install the new one. Re-install the door handle and re-insert the inner door panel carefully and gradually work
your way around the perimeter of the door glass and make sure it snaps back into place.
This repair can be done with the door in place, or you can remove it for easier access. If you decide the remove the door, simply open it all the way and lift straight up at the hinges. The door will lift off of the hinge pins. Place on a hard flat surface with some towels under it for padding. This protects the door facing from scatches.
If you have any questions, or require additional assistance, please let me know. I hope this helps you