No, the line is not in the Unity game and was added for the extended locker scene (although admittedly that was months ago in development for me and I hadn't really thought much about it since then). Part of the lines inclusion was my own mandate of "add/increase incest wherever I can", since that was one of my gripes with the Unity game. Sometimes it felt like Morty was just short of calling characters "landlady". In this game, Morty's path is mostly incest, and giving Jessica relatable encounters (all be it fucked up ones) played into the direction.
Additionally, we don't really know that much about Jessica from the show, and while her character is expanded slightly in this game, it's not by very much (Tricia and Morticia get way more development than Jessica does, and Morticia doesn't even appear in the show or comics!). So the second part (her being raped) is additional character building, with the intent to make the player feel sad both for her and for what they are doing with her (technically a non consensual path with the love bracelet, despite her dialogue).
Yes, I know, rape is not a character trait, it is the crutch of a lazy writer to use it as character building. But, also, porn game... so...