Yes, you are a terrible person, and the only thing that will save you is if you made up this story for fake points on the internet. Which, you probably did. 

AITA is notorious for petty feuds that most normal people would handle on their own like adults. But that's not how Reddit works. On Reddit, people like to think without their brains, and that's exactly what this daughter did when she decided to start sexting with her own father. 

What started out as a "prank" quickly devolved into territory no daughter should unknowingly take their father down. Eventually, the sainer of the two friends realized the prank was no longer funny, and so she tried to tell her friend to stop sexting her father, but things had gone past the point of no return, and from the story, it sounds like, in a sick way, she liked it.