My guess is You will need to go through a foreclosure process in this situation as a legal remedy.

Most lenders do not offer HELOCs on investment properties, so it may be difficult to find this product. 

That fits my needs better than YNAB appeared to and is very close to Mint. 

There are limited exceptions for properties that were recently purchased but it does not sound like that applies to your situation.

Quote from @Rachel Marshall: Talk to your lender.

The information contained in this post is not to be relied upon.

I assume this is in Denver?  

I just bought a Lake House in Maine this past summer.

@Michael SimmondsI've spoken to many investors in the same predicament; I'm sorry you're having to deal with this.

For further learning, here are some solid bookkeeping books that can enhance your knowledge:"The Book on Managing Rental Properties" by Brandon Turner – This book covers not just the property management aspect but also has sections on bookkeeping and managing finances."