I've changed my perspective hugely since having my second, very different birth.
Before I always thought my first was less than ideal, but mainly in that I felt ignored by the hospital etc. and didn't manage to avoid any intervention, which made things kind of escalate...however it was quick, and pretty easy on the pain. So no trouble telling people about it, I was confident before it and felt I would do it again albeit differently.
This time hurt like I've never known, no pain relief at all and very fast. Everyone who was there keeps saying how impressed they were, but at the time I was so traumatised that I couldn't even think about it, let alone people would come on mumsnet and talk about birth as if it was something 'normal'!
Since then (2 days ago) I find it very hard to see my pregnant friends because I don't want to freak them out, yet I know exactly how frightening and awful it felt.
I have talked about it with my friends who were present (thanking God for them now) but wouldn't wish to put ideas into others' heads about the horrendousness if they don't already know. I think they need their blas confidence more than they ever will again, but still, they might have the same filter I did when I was first pregnant, I wouldn't have believed them anyway
Take it gently with your mate and see if she asks for graphic detail before being totally honest.