I'm thinking of ghosting on a 15-year friendship
Why do you want to ghost a longtime friendship?
I'm angry with that friend because of her unpredictable behavior.
It's okay if you want to end a friendship but it's rude to ghost on somebody. They should know the reason so they can learn from it.
Ok maybe you have a point there. Learning from mistakes is the most mature thing she could do.
Its good you can realize that, and talking to her will strengthen the relationship too I'm sure. Ghosting people is so childish.