  wow I feel really sorry about that. I know how you feel my grandmother fell dead on the day before my birthday.
Just remember to say goodbye before she goes off to surgery. If she comes out ok then well that is wonder full but if she doesn't... I wish I got a chance to say goodbye. It is the one thing I really regret not saying to her even though nobody could have predicted her death.
you don't have to sound inspirational or happy and I don't think anyone would really expect you to be just feel confident that no matter what she will be ok in the end. have faith and remember you have friends to talk to. just saying I went out on a limb to do this cause last time I tried to comfort someone like this they hated my guts for it. so please don't do that! 
