What do i do?!!!

K so i have this friend, well i thought she was my best friend. i'm a couple months into my senior year of high school and didn't even think of going to college. fast forward to present day and i got accepted into two really good colleges. i would be a first generation college student and wouldn't have any financial assistance from my family. so i'm really excited and i'm planning on going to the same college as my so called best friend. i kinda give her the hint that i'm interested in attending this college and today i told her that i didn't know who i would room with. she said that she was going to room with this other girl that she's friend with. i am so beyond shocked because i thought her and i were close enough that we would room with each other. hell i even told my mom that i would be probably rooming with her. my mom is already concerned with me being b able to even afford to go to college. she has never heard of anyone in our family going to college and living in a dorm and all that. she was so excited that i was already going to have a roommate that i knew before hand and she was already worried in general because in the youngest child. this is being heartbreaking to me and i'm genuinely in disbelief because i really thought she wood want to room with me. i just don't know what to do now and now i really don't want to go to the college that i'm really like because of her. what do i do?