It was who~
- It was she who lied to me first.
- It was she who approached me first.
As far as I know, when I use 'she' instead of 'her' it's so formal, so in writing you use that way, but in speech, you tend to use 'her' instead of 'she'. Am I wrong?
I wonder which one is natural and whether it'd be fine when I use 'she'.