My roommate dropped a folded up heavy blanket on my head when i was sitting on the couch. could this cause a serious neck injury? i have a fear of spine injuries.

Overly Fearful: If you're on the computer, posting this question, without any pain or symptoms, you are perfectly fine.

Neck injury: Slim possibility, but obviously you are OK. Is there any soreness, limitation of mobility, or other symptoms? If so, seek medical evaluation. If not, you should be OK. Have a gentle conversation w roommate about avoiding risky behavior.