When I started this I read comments about how chapters 9 & 10 justifies his current state of mind and revenge. I'm sorry, after reading this chapter, aside from their initial betrayal, he put himself in the situation to be killed by him. The princess sends two minions and he just ups and believes them "just because" they say some nice things to him and claim the princess is worried about him so he goes to her and gets tricked?
He doesn't even try to negotiate to meet on some type of neutral ground where he could create an escape scenario for himself. He goes to them where they control all the possibilities, know everything about the terrain, the place he's going, etc. Then on top of this he goes with them into a secret place that looks suspicious, he asks about it sure, but he walks right in.