Emotional reminder: Personal Finance is PERSONAL.

The borrowed money is really just temporary until their primary residence sells, which given the time of year should be able to go on the market for Spring.  

It's nice to have multiple eyes on the deal, not just for due diligence and to handle issues that arise (and whoever is available takes it on), but also for emotional support too when things get tough. 

Your pain of having a 30 year note is emotional, not mathematic.

I’m prettt sure this is temporary

My point is that if you plan on holding long term the decline historically has always been temporary. 

and being on the wrong side of debt in a bad market (even a temporary bad market) is no bueno. 

Adjusting rents would add to the NOI and justify a higher purchase price.But I also think I'm emotionally attached to the building because it's a beautiful 100-year old home in a prime location.

But if your cash buys provide enough income to live for the rest of your life, nobody can fault you and you may not even care if there's a temporary down turn in the market at some point

You should feel that fear and that emotion, be glad it is there, learn to kind of embrace it.