Suzaku said that he had hated Lelouch, but when he saw Lelouch being killed by himself, he clearly felt that he was crying and his heart ached.
Lelouch was not dead. When he came back with a false identity and was discovered by Suzaku, a lot had changed between him and Suzaku.
In the end, Lelouch felt what Suzaku felt when he stabbed him to death.
(This article is bad and unfinished, please proceed with caution, it has been completed)