[It is a true thing about Elena and it isn't a thing she would change about herself ever. She went through her period of blaming everyone and everything else. That was enough for her and for everyone else.]

[She continues,] He killed an Original. When you kill an Original, you kill every vampire they've turned and every vampire they've turned until the whole line is wiped out.

[Elena doesn't think she needs to explain how that was the very quick and dirty way of finishing the Mark. It was a dangerous shortcut, but she thought it would be better. They couldn't kill Klaus (because he was the head of their line) or Rebekah (because Klaus would lose it more than he would over his brothers) and she wouldn't think to kill Elijah. So, Kol was really the only choice.]

The only thing left to do was to find the cure itself, but it was...stuck.