I had a dream about a school shooting?

Last night I had the most vivid dream of my life and the most terrifying. It was dark and rainy and at took place at my high school. In the dream I was walking down the hall when the principal declared a code red (that means there is an intruder) I started to run to a clroom but this girl, who has always been mean to me closed the door just as i reached for the handle. I heard my friend call for me from the back of the room and try to get to the door to unlock it,but he was knocked down by a mob of my enemies. I heard screams and 7 gunshots. I ran to all the doors but they were locked. I saw my english teacher in the hall and ran to him. I asked what was happening and he said "Don't you know what happens?" smiling evilly and he pointed to a student that had been shot. I ran to the library, it was empty and I went to the window but I saw a man with a gun outside so I ducked. My boyfriend that had moved away months ago, was running to me from across the library. The man pointed the gun at my boyfriend's heart and I screamed no. He fell down and I ran to him, knowing that I would die to. As a bullet pierced my back he told me he loved me and I fell beside him and he hugged me. He held my hand and told me that he would see me on the other side. A second bullet hit my head and I blacked out. I woke up sweating and crying. What did this dream mean?