"Forget the sunk costs." "Think about what would be the best move for you right now"
Aren't these essential for moving forward and figuring out what "the best move" right now is?
Not only are they (the sunk costs) not essential, they are completely irrelevant, immaterial, and likely to lead you to the wrong conclusion.
In your shoes (keeping in mind I only have the scant information you posted, no info on the rent, mortgage payment, etc.), my order of preference would be:
1) Some sort of short sale getting them to waive the right of recourse.
2) Signing the note.
3) BK
4) Keep the house.
4 however, could move up to number 1 or (more likely) 2 depending on your local housing market, the house itself, etc.
Bankruptcy is the "easy" way out, but with your salary (nearly six figures) and the small amount the debt will be (20-30k), it's not worth it, IMO.
That will depend on you as a person though.
As I said, you need to determine the information you need to make a decision, then once you have that information, solicit advice. Right now you seem to be fumbling in the dark without much of an idea of your options, the pros and cons of each, etc.
Best of luck.