Feeling anger towards someone who commits suicide is completely normal, whether they succeed or not, and I would even guess that most people feel at least some anger if someone close to them dies in this way.
It wasn't very diplomatic of you to voice that feeling to your friend and she is now pissed off, but it was a completely normal and reasonable way for you to feel.
It's a terrifying and devastating thing for you to have gone through and you must have felt an overwhelming level of fear. If you then decided that it wasn't even real and she was just fucking with you, and she did it for what seems like a really trivial reason, no wonder you were furious.
I don't have a fix for your friendship I'm afraid, I just wanted to say that all the people saying variations of ' that's not very supportive' , they must all be perfect people who never experience any emotion and never say the wrong thing.
You stepped up for your friend when it really mattered. It doesn't get more supportive than rushing across town to save someone's life, so all those people saying ' you should have been more supportive ' can bugger off. However, I can also see why she's cross about what you may have said.
Maybe read around some therapy and advice about suicide, and family of suicide to make sense of your own feelings and it might help you feel a bit kinder and more understanding towards your friend as well. Personally, I don't believe the 'its a cry for help to get attention' theory about suicide attempts, even crap ones where you don't take enough pills. I think doing that means she was genuinely in a really bad place and couldn't cope, and all suicide attempts should be taken seriously.
Beyond apologising , waiting, ( and maybe pointing out that you did rush over to save her life), there's not a lot you can do.