It's a novel. The storyline is supposed to be NTR, but it's more like rape and more rape. The original file also has an audio read along of the wife (about 150mb of audio files). I don't like this type of story, but maybe someone else may like it.

Basic storyline from DMM (ENGRISH WARNING):
The Married Woman which says beloved husband and pretty ○ attendant and Ritsuko Nagashima spending peaceful days……
Such a peaceful Nichijou is disturbed by the man who fell in love with her at first sight……
The Ritsuko which has chosen the days when Home was violated by a man to keep days of peaceful Nichijou……
Carry the ○ attendant of the man before long, and the Ritsuko which had a moment of the ruin that will come soon close at hand decides one……
Talk about days of the Torture & Rape of Ritsuko Nagashima who is Married Woman and a sequel of the So in a viewpoint of the person in question including recollection, monologue in the reading aloud form of the novel.