Looking for a stepdad Hentai

Hey lads, need help with an source I read in my early days of appreciating the arts of written hentai.

It's about a daughter of a busty mom and step dad. The daughter never liked her stepdad found him perverted and ugly. After a while he is blackmailing her with leaving her mother that and the combation that she hears those two having hot sex and the mindbreaking sex with him is corruption her to the point she starts to like it.

I can't remember much, but I remember him fucking her on the Toilette while she needed to keep quite, while her mother stands outside. It is writen from perspective of the daughter.

If you could help me out, I would be really happy and thank ful!