What does this dream mean?

i had a horrible dream last night that my brother committed a massacre in my old middle sckool,, my community does there parish festival thing every summer and one time in thunderstormed so everyone had to move inside and inside there was a flee market in the gym and in the cafeteria they would sell food and play bingo and have card games etc.. and my dream was a flashback of that so when it was over i somehow ended up outside (this is real hard to explain) and i remember i was in the parking lot and there was ambulences and fire trucks everywhere and i remember the number of people who died was 32 and it was my brother who did it and so today i was invited to a graduation party in the same cafeteria becuzz the school does those things and i didnt want to go becuzz i thought something like that was really gonna happen becuzz seriously my dreams have come true in the past!! soo what does this dream mean?