The Black Figure?

This is a story from about 20 years ago. I was bitten on the ankle by a dog being kept by someone else and suffered a serious injury. I was hospitalized, underwent two surgeries, and overcame cellulitis, among other things, to be discharged safely. During my hospital stay, my post-surgery wound wasn't healing well. When my ex-boyfriend came to visit, he said things like, "You must have done something to provoke it, right? You idiot! You got what you deserved!" and hurled insults, which devastated me. For a while, there was no prospect of being discharged, and the days were tough. One afternoon, during my daily IV drip time... Normally, I had the IV in my left hand, but after daily use, the vein had hardened and wouldn't accept it. "I'll put it in your right arm. You'll be facing north, but can you turn the other way?" I was told, and obediently turned over. The needle went in smoothly, and I usually read during this time, but I dozed off. Then, I suddenly heard a voice from behind, "It's your fault!" I tried to turn around, but my body wouldn't move. Repeatedly, the voice muttered, "It's your fault..." and got closer and closer. A chilling air stuck to my back, and finally, a shout right by my ear, "It's your fault!" Whether I fell asleep or lost consciousness, I don't know. At that moment, I clearly saw a pitch-black shadow? I wonder who it could have been?