Aslan's people think Edmund is healed.
It's mostly true. The White Witch's direct control over his mind is broken. He fights with his brother and sisters, now. He will never fall for her old tricks again, will never go back to her castle, or drink of her cocoa, or eat of her Turkish Delight. He knows his mistake, and he will never betray his true friends again.
He cannot forget the time when he thought she loved him. When she offered to make him a prince, *the* Prince, instead of just one of four. When she told him she'd give him everything he ever wanted, if he just did this one small thing.
He knows she was lying, knows he would have ended up Prince of a hall of statues. But he still hears her voice, wheedling and promising, in his mind. And he knows he loves her still.