yeah but when he do he's crying like a bitch LOLOf course he Cried, He just found out that everything he ever thought about his parents were wrong. He found out that his mom really did love him, and he had to seal away his own dad. Come on now. That's a perfectly good reason to feel a little emotional considering he rarely ever shows his emotions in the first place.
Just think about all the people he has killed, and for what? He thought everybody hated him, he thought his dad wanted him dead and his mom hated him. He found out that Yashamaru was forced to attack him and blow himself up.