I came across the image below and I found it incredibly powerful.
While it applies to any form of suffering, it is very common for the abuse between siblings to be ignored or dismissed. Society tends to downplay problems between siblings and categorise them as normal family dynamics. They are not always normal though.
Emotional, physical and sexual abuse all have long term impacts on the victim and when people around you act as if nothing bad happened it can be devastating. On top of that you are also expected to remain in a relationship with your abuser by family and friends.
This adds another layer of violence to what has already been suffered.