Is it possible for someone to have damaged my rear compression control arm? Because I have not hit anything for it to break in half the way it did.
Anything is possible. But it would be difficult for someone to cause a small enough amount of damage in order for it to break at a later date in time. It would be more likely that a pothole or parking block covered in snow would be the culprit. Maybe someone else was driving and mistakenly forgot to mention it.
The knuckle, camber link, compression link(8) and tension link are aluminum castings. Extra care needs to be taken when servicing these components. The wheel and tire mount at the end of the knuckle(7).
Unless you have recently had some work done, I do not think anything was done to it to cause it to break.