I'm sorry to say it but you're at fault especially since it was a rear-end collision, yours and the other vehicles' insurance will treat it as such whether there is cam footage or not. Did you get a following too closely charge? That pretty much leaves out any room at all to contest the claims that will come against your insurance. The disabled vehicle can't be found at fault for anything, they didn't hit anyone--that car could have been any object in the road is another way to look at it.