It's a horror film based on an Edgar Allen Poe story?

I'm looking for a film I saw at least 12 years ago (probably more) that features a woman who is being cheated on by her husband. As it turns out she has a deep seeded fear of being buried alive, so the husband and mistress put her in a coffin when she's unconscious. She breaks loose and kills the mistress. The final scene of the film is the woman on the kitchen floor with a knife. Anyone know what I'm talking about?