what actually happened?

Last night i had this dream which felt so real to me! I, myself dun know how the hell did it happened...out of no where, i dreamt of an old friend of mine. Haven seen her for some time already, she used to be in my school then shifted to some other school, cross my fingers k? touch wood, i dreamt that she died, yes it may sound mean and cruel but do u think i want that? it really felt so real, in the dream i was there when she "died" and i couldn't do anything to save her. i was crying like mad in the dream. Can anyone explain to me how did it happen? i always dream but never bout someone dying....this is not right. And then i saw her online this morning, thank God She's fine.....!