Your request made me go "le gasp!" but it seems to have worked out. I'm a bit fuzzy on whether/when this would have happened, so I hope I didn't mangle canon too badly.

For the longest time, everyone had been able to keep it a secret. Edmund never knew what deal Aslan had struck with the White Witch, though in all the excitement that came after, he all but forgot about it.

Now, though…he tried to wrap his mind around what he had overheard. Aslan, killed by Jadis? It didn’t seem possible, not least because he had seen the Lion the very next day, alive and well. And that he would have done such a thing for Edmund, the traitor…Edmund shook his head, vision blurred with tears. He would have to ask Lucy.