How much of the 52 units do You own? 

If you hear from him again or an attorney, be sure to respond immediately by your own attorney if necessary.Not sure what the laws are in your state, but you want to do whatever you need to to confirm the tenancy has ended (whether that is by abandonment on his part or with proper notification to end a month to month)

You are free to do whatever you want after. 

I know you mentioned taking time to relax, do you plan to further scale or do something different outside real estate?

Do you also use Redfin/Zillow as a starting point? 

Ask very specific questions if you do. 

In many cases, the services are overly complexed and do nothing but add additional recurring costs to the client (which these service providers often benefit from).

They are typically less profitable as condos do not appreciate as good as single families.

Probably your best bet will be to do a joint venture with an equity partner.

But we do not want to sell our current home.