Here is the full excerpt
You remember the dragon that you brought Vader forth from your heart to slay. You remember the cold venom in Vader's blood. You remember the furnace of Vader's fury, and the black hatred of seizing her throat to silence her lying mouth—and there is one blazing moment in which you finally understand that there was no dragon. That there was no Vader. That there was only you. Only Anakin Skywalker.
That it was all you. Is you. Only you.
You did it. You killed her.
You killed her because, finally, when you could have saved her, when you could have gone away with her, when you could have been thinking about her, you were only thinking about yourself... it is in this blazing moment that you finally understand the trap of the dark side, the final cruelty of the Sith—because now your self is all you will ever have.