Just avoid the "at least your baby is healthy" consolation line. People often say this to help mamas feel better, but when you've had a traumatic birth what is really says to mama is that how she feels doesn't matter as long as her baby came through in one piece.

So definitely steer clear of that little gem

Other than that, just let her talk. You don't have to say anything. You were a friend who was supportive of her goals for her birth in a culture where women often don't get ANY support like that. That's such a gift. Continue that support by being there for her now, and let her talk and don't try to make her feel better just yet. She will probably have alot to work through so, someone who just listens to her without belittling her feelings with the healthy baby blabber will be much needed and valued.

I hope your friend recovers well, take care.