I'm of two minds on this.
Yes, Carla's methods guaranteed that both Billie and Ruth were outed to the entire hall in at least three ways, and that's bad. And, although Carla didn't know, it potentially puts Ruth in a worse situation in the long run.
The counterpoint is that, had Carla not dragged it into the public eye... Mary's psychological torture would have still held power (and Carla was very much a target of that as well, remember), and Billie and Ruth would have continued their suicide pact without professional help. And, should that have been allowed to fester?
A third option would've been to go directly to the RM or to call 911, but that still would have risked Ruth getting fired. It at least may have kept Billie and Ruth from being outed as much as they were though...