Very Bad Things: The Next Generation
This reminds me a lot of one of my favorite black comedies, 1998's Very Bad Things (http://www.imdb.com/title/tt0124198/). If you haven't seen it, and if you 'liked' this, you should definitely check it out.
In some ways, Ward's Wife is even darker. If only because it's so completely well-adjusted and amoral and less exaggerated, and it doesn't just fall completely into comedy in the end. Instead, the film takes its concept of the banality of evil and pushes it all the way to the edge -- and then right over the edge. (The husband pissing on his wife's corpse is an image I won't soon forget...)
This also reminds me of The Last Supper, from 1995 (http://www.imdb.com/title/tt0113613/), for the idea of killing someone you don't like, or simply find unpleasant...
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If we could see ourselves as others see us, we would vanish on the spot. - E.M. Cioran