<human>: Could you distill the essence of the text into 1-3 sentences?

Hi there, long time lurker, first time poster hoping to entertain you with my fuck up.

So...here goes. So my girlfriend and I are currently in a long distance relationship after she moved back to Shanghai after she graduated from university. Our medium of communication is normally Facebook messenger, this part is important, you'll understand why in a moment.

Shes moves back and we have had some rough times from not seeing each other so the moment we both have free time (it's not very easy with the 7 hour time difference), we escalate the conversation into something very explicit.
This was fine and all, until hours later when our world fell in to a fucking mess. HER 14 YEAR OLD SISTER WAS PLAYING ON HER IPAD WHEN WE WERE SEXTING. Holy shit, how the fuck did that slip past us. Fucking messages were popping up on the ipad while she was playing some fucking game and I think we scarred her for life. 

Best part of this story is that my GF asked her sister what she saw and her reply? "I didn't see much but you really like it rough in the cat apparently" The most innocent response I have ever heard she couldn't even say it. I'm done with this world.
<bot>: Sexted my girlfriend on facebook messenger while her 14 YO sister was playing on her ipad which also had facebook messenger fml.