Do you presently reside with a person, other than a spouse or legally recognized civil union/domestic partner, with whom you share bonds of affection, obligation or other commitment, as opposed to a person with whom you live for reasons of convenience (e.g. a roommate)? If so, complete the following. If the person was born outside the U.S., provide citizenship information.
If I live with family do I list them here?
Question 21 pertains to Psychological/Emotional health. If you are asking about cohabitant, it is anyone you are living with in a spouse like relationship. Family members are listed in section 18, Cohab or spouse are in section 17.
No, you don’t list family members as cohabitants.
I remember having to list my spouse as my cohabitant and as my spouse… at the same time (after being told to do so), then being asked “oh are these two different people?” 
The person that told you to list your wife as both didn’t know how to fill out the SCA and gave you bad information.
and they are part of the issue that delays security clearances.
The information on the SCA (SF86) is used to make several determinations. Bad information, poor attention to details, laziness, and “oh, they don’t really care about that” omissions creates a huge mess when it comes to field work.
Such doing work that was not necessary while having to start work late in the process that was never scheduled because of omissions. … or delays while an investigator goes out to talk to you about why you have a wife and a cohabitant (even if the names are the same).
The issue is that you get a POC who is supposed to help you out (especially if its your first time filling out the SF), and they have no knowledge or training in any of this.
For those who are trying to ensure that form is filled out correctly, and take the time to ask questions to the POC they’ve been assigned, it’s not like they have a BI to speak to while filling out this form… and a lot of people prefer not to ask questions on public forums.