sexy black halter - long blouse or short dress

This was a gift and I wore it once. It is very flattering, but I can't justify keeping something I never have the opportunity to wear. It is make of very thick, stretch material and has supportive boning in the bust. There is a sheer halter overlay with elegant button details. I'm not sure if this was meant to be a long blouse or a mini dress, but it can be wore as either. Listed as medium, but could easily fit a small. Open to trades and offers =)