llymo, I'm so glad you decided not to go. I wish I'd checked in and written so yesterday.
The friendship with your friend is something very personal. There's no need for you to make public displays. Maybe some day you can talk with her mother about how much her daughter means to you.
You understand your feelings very well, and please honor them.
I've had wonderful experiences at celebrations of life. One friend arranged for her celebration to be held a few weeks before her death from cancer. She said "I want to be there so I can enjoy it!" And she was and she did.