I wouldn't say that Peragus could be considered her fault
You mean just like the devastation of Katarr couldn't be considered her fault because she didn't count on Nihilius to screw the whole planet up? She's a hypocrite, simple.
She blames the Exile as soon as she comes to know that she's been on Peragus. And she acts surprised that the Sith have revealed themselves, thus trying to hide the fact that SHE was the one who made the Sith reveal themselves.
I think Atris didn't care whether the Exile lived or died. She publicized the news of the Exile's return knowing very well that this would put the Exile's life in danger.