Certainly very scary and shocking to look at when you see debris from the ceiling everywhere. Unless you were highly unlucky, I doubt this would have killed you. Especially since you said you had a roommate who rushed to the room immediately. He would have been able to get you the medical attention you needed. If you were alone it would definitely be dangerous as you could have a serious head or neck injury and not be able to get yourself out from under the debris.

Did you ever find out why it occurred? Was the ceiling buckling before it happened?