As much as Alec wished he could believe that maybe it hadn't really happened, he knew that it had. He'd seen it, even though he couldn't quite remember it. He'd seen the blood and Jocelyn's body. He'd seen Clary's grief. He knew it was real. And he hated himself for it. Maybe if they hadn't tried so hard to save him when he'd used the adamas to try to find Jace, Jocelyn would still be alive. After all, Valentine had likely only sent the demon so he could free Jace. And Jace had only been locked up because of him. Because Jace had wanted to save him.
On some level, he knew that Magnus was right. That it wasn't his fault any more than it had been that Mundane girl's fault that the demon made her kill someone. But it was so hard not to blame himself. Not to think that if he had somehow been stronger or better that Jocelyn would still be alive. "I let a demon in, Magnus," he said quietly, the words punctuated by a soft sob as he slumped forward against the warlock. "Everyone keeps saying it isn't my fault but...it doesn't change that Jocelyn is dead and that I killed her. How am I supposed to...how can Clary ever forgive me for that?"