Film about parents who get revenge on man who killed their son.

Hello, new to this site. I hope someone can help me with the title of a great film I watch a couple of years ago. The plotmgoes something like this:

A man and a woman are having an affair. Their car breaks down on a country road, another car stops and they shoot the driver. They push the car with his dead body into a lake. The parents of the dead man create an elaborate plot, involving making him believe someone (possibly the dead man) is still alive. They do this by dressing up in a disguise They then lure the man to a hotel where they kill him.