I have the same problem. I have tried to start from scratch as single and as separated. It is requiring my ex's info and I do not have it. How do I proceed?
As per the CRA, you must enter the information of your "spouses" or "partners" even if you are separated. If you do not know their Net Income CRA advises you to enter an estimate. For more information contact the CRA at 1-800-959-8281.