To go dark, you simply stop initiating contact with him.
I would recommend that you make sure you have at least a weekly counseling appointment, to help you get through this process. Divorce takes awhile, and it is scary and sad...you need support.
Do you also have family and friends to lean on? You need to make sure you don't spiral down into a deeper depression. You may even ask your doctor for a temporary script for anti-depression meds.
