I think she either lied or evaded the issue. The reason I think this is the same reason she didn't tell any of her friends or Dawn or Giles: they were all too close to her. Telling someone she loved would make it more real than just admitting the truth to Spike.

That's true but at the same time I kind of don't think she would lie to Angel about being in a hell dimension because he suffered for a long time in one himself and knows what it's like. He would probably be horrified to think of Buffy being in hell and suffering like he did. I think it would be easier for Angel to deal with her resurrection knowing that she was at peace and happy when she was dead. Because he wasn't personally involved with her resurrection and not really in her life I don't think she would feel as obligated to put on a happy face for him. Maybe she just avoided talking about where she was when she was dead but I really don't think she lied to him and said she was in hell. She only said that to her friends because that's what they thought. I don't think Angel would think that though, he's too wise.

They assumed she'd been in a Hell dimension though because her death had involved a portal to one. It wasn't like any judgement.

Tbh I think it's more likely she just avoided the topic entirely and didn't say anything. Angel might not have expected her experience to have been exactly the same as his or to have affected her the same way because they would have been in different dimensions.