I agree, it was a terrible scene, & it never even seemed like Willow understood why Tara was so upset or why it was wrong
I think Xander just kinda trusted in what Willow said, because he didn't know much about magic. In Anya's 1000 years, you'd think she would have seen some resurrections & wrong they can go
& for Tara... idk, she respected witchcraft a lot, so it doesn't really make sense to me that she would go along with it, I guess they were all just desperate