Can you tell my why i dreamt of this?

Well this morning i woke up sniffling like i was crying, but no tears were coming out. i was upset because of the dream i was having that night, which was about these two girls who will both go to my high school. okay lets call one girl Mary and one girl Sammy. Mary is still my friend, we are in 8th grade and have been friends since elementary school, although i am trying to move on from her because she is not that great of a friend. Sammy got mad at me and Mary last summer, and she was so mad that she erased our emails and our phone numbers even after we sincerely apologized, and stayed mad for quite a while, into the 8th grade school year. Well now its the end of 8th grade and Mary and Sammy are friends again, so Mary is friends with both of us but it seems like they don't want me to know they are friends because I am still not friends with Sammy, nor to I want to be. I dont dislike Sammy because of what happened and I am not sure how she feels about me. Anyways in my dream it was the first day of high school but we were all in the playground of our elementary school. i was on the swings with my two good friends, but they left to go play somewhere else, and i stayed on the swings. Sammy started pushing me really hard, making me go really high and twisting all around, almost hitting the person on the next swing. I was crying and yelling at her to stop, and yelling at Mary, who was standing there and lauging, to make her stop. They both continued what they were doing until i jumped off the swing and yelled "F*** You" at them, still crying and really mad, and walked over to my other friends and told them what happend. they sympatized for me and helped me get inside to the school, which is our middle school, and told the principle. Mary and Sammy didn't get in trouble because i woke up after that. I wonder what this could mean? And does it have to do with that fact that i am nervous for high school because my really nice friends are going to a different one and i have to go where Mary and Sammy are going, where they are going to be on the cheerleading squad?? whereas i am not and i dont even know if i will join any kind of club yet.