Most Helpful Girl
I think your feelings are justified. I'd suggest unfollowing as it is the best of both worlds: you don't have to be reminded of her on facebook and she'll never know you did it thus doesn't cause drama/give her the satisfaction of knowing she bothered you.
Most Helpful Guy
Unfriend her you don't need to do that top yourself and if she feels it was childish then you also don't have to explain your reasoning. She's your ex