Well YIKES!!!
That is a sticky situation but you might be okay - there are a number of mermaids and which ever one got crushed might not be the one you need right now.
Use Xignal's site to check maps and see where you are :
http://www.volberding.com/WHints/index.html
Somehow I don't think the mermaid you need to talk to CAN be killed so I think you should be okay once we figure out where you are. Locate your position on Xignal's maps of this area and let me know!
What is your next recent save to this area?? You may have to replay a bit if you truly are stuck!
Wyv