The ADU now covers over half the mortgage + additional monthly income per horse the tenant desires to keep on site.

That said, there is a break even point to determine that and I do not know your financial situation now.

Just in my building a 2/2 went from 800k, its now asking 625k, I wish you good luck 

Depreciation, mileage, home office, meals, 401k (assuming earned income a real estate biz) are all things to consider when wanting income higher so you can have more access to capital.Most decent lenders will give you credit for depreciation, however.

My husband and I have a house with no mortgage and great credit, but no cash to invest right now.

I'm new to BP, but have been listening to the podcasts for a while now and I definitely think it would be beneficial to separate out the regions and key words as there seems to be a lot of chatter about Rochester on here!

Now, she wants it back.

Any tips on how I should potentially navigate this differently?

Either way,  you now have a home and can take leverage :)  

What kind of work are you doing now (sounds like your own business)?