The funniest thing about this scene is 

This is literally where the game starts screaming at you to not kill. You killed Toriel? Well you didn’t know you could save her, it’s a mistake but it’s done now. You killed Papyrus? The dude was sparing you, okay you have no excuse. Why would you do that? You kill Undyne? LITERALLY WHAT THE FUCK IS WRONG WITH YOU. SHE WAS FIGHTING FOR EVERYONE. You kill Mettaton? LOOK AT EVERYONE LOOK HOW SAD EVERYONE IS. WHY HAVE YOU NOT LEARNED YET. You kill Asgore? ….Eh. He kind of deserves it and even asks for it but still you’re a jerk. You kill Flowey? YOU HAVE LEARNED NOTHING.