He doesn't know what to do. That's the issue, here. Yshae had taught him how to control himself, how to focus inwards when he was angry, but now he had failed and he's not sure how much that would help.

"I had planned to not go on any more missions." He managed the Nevarran one fine because there was no giant flesh beasts. "Now I don't know. I don't want to risk the Inquisition for something like this."

Or the other qunari. This shit looked bad on them, too.