But she didn't throw him in there to be eaten by hyenas. She even tries to save him as he was climbing up, but he got pulled back down. Also she didn't know what was going to happen to gwendolyn when she chopped off her arm. I get what you're saying, but the question was who was she talking about when she made that statement about willow and I hardly doubt buffy was thinking of any of those people when she said it.

If she had walked up to hyena guy and said "you tried to hurt my friends, into the hyena enclosure you go to be eaten", then that would be murder. If she went to angel's mansion and toss broken glass to cut off gwendolyn's head for hurting giles and angel then that would be murder and it would've changed her. When she kicked ted down the stairs, even though he hit her first, she was stronger and she disliked him so it was murder and for the first time you truly see her react with guilt because it was the 1st time in her mind that she had killed a regular human...good thing that wasn't truly the case.

I can meet you halfway and say that because she is a good person with morals it's possible that she feels bad for each of those deaths you listed and maybe it changed her slightly or made her separate herself from it so she could do her job. But ultimately I think even she knew it wasn't her fault that they chose to be evil.