I can understand why this is a particularly disturbing memory. Whatever their reasons may have been, it is clear you were a forced participant. It's frustrating to not understand why, but when I've gone down this road myself, learning why has only ever made me feel worse.
I'm so sorry you went through such horrible experiences, but it wasn't your choice. I hope you can find some peace with it as you have with so many other memories.
Thank you for sharing this.