My friend left this envelope at my house that contains her medical files...?

What do I do? My friend laura left this opened envelope at my house that she was carrying around and it contained her medical problems. I really shouldn't of looked inside but I did. Then I got really worried and then told another friend that I was worried Laura was upset. That friend told her that I was worried about something and then Laura asked why. Then I came out with it all and she was extremely angry and upset about it. She also blamed me of pretending the day before- because we went on a school trip together and I was acting weird. I didn't tell her I opened the envelope straight away and she is really angry. I am really worried she won't talk to me. What do I do? I have already said sorry and talked things over- but things seem to be akward.