When is it time to let go?

[Harold Newsome]

I bought a triplex in 2007 through Countrywide. It was my first investment and went bad fast. They required no inspection or money down and did some creative financing so I could purchase it. 

I soon learned that the foundation was sinking and the property slowly falling backwards. The renters all moved out and I relocated for work. I've owned it for ten years and it's unrented because I'm concerned about renter safety and my liability. 

I've never missed a payment, but the $1,100 is tough to manage, so I have two questions:

1) When do you cut your losses and bail?

2) If I walk away, do I just stop paying the mortgage and allow the lender to foreclose?