Many people have been wondering about sasuke's reaction. Well, this is the most accurate answer: "sasuke is not aware of leaving a kid behind although he must have acknowledged having a private session with sakura." sakura never told sasuke about sarada because she's still awaiting sasuke's return to telling him in person. So sasuke reacted in that manner out of ignorance of the existence of a n uchiha other than him. There you have it. Your answer.
