Jon isn't out to hurt her, she has no reason to betray him. She hasn't really betrayed anybody, so I don't know why people think she will. She lied to him, which was bad, but whatever, she's trying to secure her safety, so.
I hate when writers turn victims into villains, but I don't think that's happening here.
I doubt Cercei is dying tonight. She will confront one of her brothers before that.
However I think Loras is a given (being shown in just one episode and being killed the 2nd episode he appears a la Osha and Rickon), and Margeary is likely as well, I mean theres a reason if Olenna is not in KL anymore.
(and this isn't a spoiler i'm just saying)