Killer Sex and Suicide Blondes (2004)

Gem is a young woman trained as a professional killer by her fiancée Nick, a professional assassin-for-hire. But when Nick is murdered by thugs on their wedding night, Gem changes her image and looks and goes into the dirty underworld to locate and kill all the thugs who were responsible, while she continues to be haunted by Nick's ghost who encourages her to continue killing to fulfill her enjoyment of it.