This happened to me with my friend from work. I actually wrote a poem about her. She went in for a surgery and didn't make it out. She text me the night before the surgery telling me she was nervous and I told her everything was gonna be alright. Next day she does on the surgery table. Ironic enough she was a friend from work and when I came back to work from my knee injury they put me in her old spot. Bittersweet for sure.
I'm so sorry about your friend.