I'm not actually pissed, more just very lightly disappointed. "Your sister" was fine, I am just nitpicking because it's such a brilliant show that that's all I can do. It's just that "Only Cat" was such a memorable line, and I thought they were setting it up because Lysa specifically called her Cat in the previous episode. Honestly (more nitpicking) I'm more disappointed that she screamed when she fell. The silence in the books was super Eyrie eerie, it was lovely. But I couldn't really give a shit about either change, considering <90% of the changes they make are for the best.
I do wish they left the "I poisoned my husband" reveal there though.
Also the title of Episode 8 is "The Mountain and the Viper," which was revealed before the season aired, haha.