*sigh* Fine. I'll kill literally EVERYONE, making me a monster even more than Flowey, a soulless being. Are you happy now that I'll literally be breaking my game and my heart? (and by breaking my game, I mean that once you do a Genocide run, your game is tainted forever. it will never let you forget that you once killed everyone.)
Once you finish the game. ;) You can murder everyone up til then without breaking anything but your heart. And Sans'. But you can go all the way to chatting with Asgore before you're in any danger.
But yeah. I know you mentioned seeing a geno video before, but it's worth it to at least watch it again. Some of the differences in how characters react to you are great. And, you know. I'm a jerk who repeatedly starts geno runs and breaks off at various points to watch the way different people grieve. >_> I might have a Flowey account here.
You don't have to! It's a pretty cool thing to play true pacifist and then leave the save file at that forever. But I do advise at least opening the game once, because something special will happen the first time you open it after a true pacifist ending.
I have seen Flowey ask me to do the True Reset. I'm waiting to do that until I'm positive I'll do the Genocide run. I mean, I've pretty much decided I will eventually. But the game is too fresh in my mind for me to do that right now. I think I'll wait. Or reset and watch my friend play for a bit.