"There is no emotion, there is peace."
He can't deny emotion and it is foolish to try. Emotion is a man's compass. His compassion led him to go to war, the righteous anger to victory. His emotions will see him to his goals and he wants final, lasting peace. But then why does this feel wrong?
"There is no ignorance, there is knowledge."
Revan never explicitly believed in a Light or Dark side. The intent behind the action is what matters, isn't it? If you wield the "Dark side" to benefit others, is it evil? But perhaps that doesn't apply to the Star Forge. Perhaps the bittersweet taste in the air and the way it soothes his mind yet twists unpleasantly in his gut is the Dark side. But he would use this to help the Republic. All things can be turned to good.
"There is no passion, there is serenity."
This war is his passion. The Republic's safety is his passion. And through this passion he will find serenity. He will build it. This was for the best, for the benefit of everyone. He was helping a Republic that could no longer help itself. A great threat is lurking on the fringes of known space and the battered, unstable Republic cannot stand against it. He would unite it, lead it. He would piece it back together and save them all.
"There is no chaos, there is harmony."
They would condemn him for this action, surely. Say that he turned to the Dark side. But that was far from the truth: the Force guides him. From the chaos would come a fragile sort of harmony. And he would strengthen it. When it was over, they would hail him once more as a savior, not a villain.
"There is no death, there is the Force."
The Force led him here. The Force asks for this, it demands more death. The Force will lead them all through these difficult times. The death will stop eventually. The Force will guide him.