Well, it depends a lot on how much your tenants care about their Credit Score.Sadly most Collection Agencies I've worked with tried to "make a quick buck" meaning use scare tactics to make the tenant pay before formal litigation.

If the OP wish's to escalate this to civil court remedy.

Pretty much stating I won't let this go to litigation/eviction for any missed rent (didn't pay for Feb) or damages.

If you as an investor plan to approach homeowners in California to purchase their property after a NOD has been filed you definitely need to read (and reread) California Civil Code 1695. 

Civil records clerk claims the only forms they have are landlord/tenant eviction based on non payment of rent and I need to google the form I need. 

Still we all tried to be civil while my husband and I asked what we wanted to know.

Development and managing a site is much different than building. if you aren't experienced I'd find an experienced zoning attorney or land planner or civil engineering firm. 16 units for 3 acres is pretty low density, extremely low density. have you looked at future overlays for the project to see how many units you could get?

Perhaps a family law attorney opens back up the divorce case and pursues the ex to judgment, perhaps a real estate litigator gets involved on a contingency basis or even deferred hourly if he/she can pursue treble damages for fraud, etc.… who knows.

Was there negligence here and is some sort of litigation something I should be considering?

I had a business in an LLC and I overheard a customer talking to another in the waiting room saying he does OK suing businesses for small amounts since litigation is such a PITA, not knowing I was the owner.