0.
You'd think that the pain would cloud his thoughts. That he could spend these his last moments in some ignorant, happy oblivion. But he can still feel the burning, feel the fire as it creeps up on every part of him, and somehow even with this he is thinking more clearly than he has in months. He can see everything.
The man who was once his master stands above him, looking like he is in pain, but he is not the one laying limbless and ignited on the Mustafar sand.
Anakin thinks back to the many times he saved that man standing above him. He used to keep track. He'd remind him of the number every time. Eventually he gave up on that childish game, but he knows the count is at least above fifty.
Obi-Wan does not return the favor. Does not return one fiftieth of it.
"You were the Chosen One," he says with a helplessness that makes Anakin want to laugh, but his body says no, there is too much energy elsewhere, trying to keep him alive even though there's no point in that.
Only because you believed it, he thinks instead. And he hadn't realized that Obi-Wan believed it. His master never used to speak about it —or about anything, really— and for a while Anakin thought there was at least one person in the world who did not have those ridiculous expectations for him. But maybe it was just hidden, all lies.
And then Obi-Wan destroys that last hope even further, goes blithering on about how he was supposed to destroy the Sith, when no one ever told him how, no one ever showed him that the Jedi way was any better, and then his old master simply outdoes himself and ends with a pathetic— "I loved you."
It should hurt, but Anakin can see the place where his hands used to be and smell his own charred skin, so he has no time for Obi-Wan's selfish words, said only to reconcile his old master with his own guilt and loss. Because Anakin loved, too — he loved so many, so much, except for him it was intemperance, a breach of the Code. But for Obi-Wan? Obi-Wan can love all he wants, for Obi-Wan's sins won't tip the balance of the Force.
Only Anakin's will.
Now Anakin's have, and he wants to laugh in the face of all those who hoped he would fix them, because they were the ones who led him to this. They saw the one who they believed was chosen, and they left him to rot, for the Chosen One must need no help — the Chosen One must be let alone to bring balance unhindered, so long as he follows the Force-forsaken Code, so long as he executes their orders without question or error —
Obi-Wan lets him alone one more time, alone with the fire and the rest of his body beside him.
Is this balance enough?