So basically Rapunzel_is_a_Ginger:
Snow is guilty of murder by association. We all know that it was her manipulation of Regina’s need to feel love which ultimately caused Cora’s death. This one act of manipulation is what caused the whole thing to go down. True she was evil and it gave me chills when she said it. I must say I even loved her playing with the dark arts so to speak.
My point is that Snow is not upset that Cora is dead but for using Regina to actually commit the act. So I guess she will only be able to move on when she accepts why she had to do that. Why it had to be Regina. Which I believe until Regina sees why her mom had to die, Snow will not be able to accept her part in the situation.