After getting his soul back, Spike is visited by his victims, one by one. He cowers in the corner while they parade around, taunting him.
He’d wanted to be a better man for Buffy, but he hadn’t thought how his conscience would affect him. He’s never stopped to think about all the people he’s killed. He had grown to care about Buffy and her damned little Scooby Gang, but he would still have happily chomped down on an innocent stranger if he could.
He understands now, how having a soul kills you from the inside.
From beneath you it devours.