do you think willow's actions after Tera died were justified?

Killing Warren - Yes. He was too much of a problem.

Everything after that - completely overblown.

Absolutely.
She shouldn't have bothered fixing Buffy though.
Buffy wanted to be dead.
Then later when Giles powered her up - more... well who else has ever connected with EVERYONE on the planet? Who better to make that decision?
If the Red Witch says humanity needs killin', I say get with the killin'.
She seems to know what she's talking about.

i think it would have been justified if she actually killed andrew and johnathan to...but turnin on ya friends who is more like family hell no she wasnt justified with all that...im glad xander saved her sanity nd the world in the end

I think they probably are justified, i mean its not like he was innocent but willow did not have the right to take his life no matter what the circumstances. she lost herself in the process of seeking revenge and tara would not of wanted that.

Yes because Warren was just to annoying and psycho but then she took it to far and tried to end the world.