This is gonna suck.

I'd essentially treat it as if you'd dies and had to return to your home point. You'll need to head back to the Amal'jaa stronghold in the NW section of Broken Water and search till you find the right instance spot. I can't remember if it involves simply heading into the central area or one of the surrounding caves.

Sadly, trial and error on location (unless your journal shows a destination point with a map).