How awful for your friend.
I haven't been in that situation myself but did experience someone dying and I found it hard to cope when people asked 'How are you feeling?'
I know they meant well but how did they think I was feeling? Its not a question I could answer. I think the best thing I heard was 'I'm sorry for your loss'
Then if I wanted to talk about it I could, if not then I could just mutter thank you.
Agree with the others about sending a card to say you are sorry and that you are thinking of them at this difficult time rather than finding a poem to send.
Perhaps you could send a poem to mark an anniversary or something similar at a later date, just not yet though. Its a lovely thought and I am sure your friend will appreciate having you round to support her.