Trying to remember a doujinshi

[Teshirn]

As the title stated, I am trying to remember a doujinshi that I read in the past. Plot was basically a married mother being intimate with her step-son. The father found a condom and put a webcam on to see who is responsible for the condom. He realize it was his wife and his son, but for some reason keep masturbating to the recorded video. In the end, the mother was pregnant with her step-son. This was all in full color I believe and I had read this on Fakku before it became a paid site to read. Hope, all this information help :).