But she did. She chose to stay alive when the entire conspiracy hinged on her sacrificing her life, either in a gunfight at Sickbay, or preferably down at Engineering, blowing up the ship now that she knew she had been exposed. She betrayed the conspiracy to save her own hide - why would she have been more oriented towards self-sacrifice earlier on?This is making the assumption that Valeris expected to survive.
It would be simple enough for Chang to promise to beam out Valeris at the last second in the starship fight where the Enterprise and Gorkon's ship would slug it out. And it would be even simpler for Chang to fail to deliver on that promise.
Why should it? Both sides could be working on the assumption that when the backstabbing begins for real, they will be ahead in the game. Chang will have absolute command of the meanest war machine in known space, now boosted by a ship that can fire cloaked; Cartwright will have eliminated his own doves and will believe in Starfleet superiority just as much as his right-hand man.Cooperation on that scale requires trust.
Clearly, the conspiracy is not about maintaining status quo, despite possible appearances. If Chang did that, the Klingons would lose and die. If Cartwright did that, he would let slip the first chance in seventy years to kick the Klingons when they are down, and then keep on kicking until the last wrinklehead was phased-matter dust. It's all about taking advantage of an unique opportunity to make peace by going for the throat.
Timo Saloniemi