Because in the movie 1, he turned a blind eye to Hawking's son's life and death in order to complete the task, which led to Huo Xing's (real) death. Later, he said, "This is the best choice among all the schemes", so he wanted to self-destruct.

3( 1) He saw the scene and remembered that Huo Xing (really) died because of him, and the trembling of the body also played a role.

(2) The flesh trembled. At that time, I just said "Huo Xing" and could not wake it up.