The look that Kaidan gives Alistair in that moment can only be described as murderous. The one thing that wasn't permitted was giving away Warden secrets, and what did he do? Give away the biggest of them all.

In the future he might think about how it wasn't so bad that people knew, but right now? All he wanted to do was take Alistair outside and thrash him. He would be right. Weisshaupt wouldn't like it at all... but it was done. It was out there. "Now you know why we've gathered here," he ground out, unimpressed at having to say the words, but they were there.