Now of course you're battling zoning constraints. 

To add to what @John Woodrich said about cash in general - yes, avoid it.It is possible to win a battle with the IRS when you paid cash, but it is not easy.

If you decide to have her stay I would not get in the middle of his court battle, she can file a restraining order against him, he will still owe on the rent but not be able to legally return. 

From there, you have to decide how to handle this;  For sure this is a loss, because you have to spend money on unit turnover, down time from leasing, etc..Normally, I try not to engage in battles. 

Sometimes you have to pick your battles.

Knowing what you are good at and not good at is half the battle.

I battle with this myself, so I sympathize with your wife.

The numbers absolutely work while living here, but they only work after moving if we can rent it out room-by-room, and so long as I'm on top of my rental management game to battle extra vacancy (they also work if I wish to hire a property manager, but I'd rather not do that until I have more properties than I have time to manage so I can learn the ropes). 

I prefer civil and must say my first day on Better Pockets felt like a battle zone.

Finally, building key, strategic partnerships can be an uphill battle at first, so confirm that you can leverage their relationships and track record, so that you can actually be in position to do deals.