My best friend is taking me for granted !!!!?

My so called best friend and i were supposed to have a sleepover about a month ago it was going to be a special girls night movie marathon. then a day before i phoned to make sure she was coming over still and she told me she wasnt because my other friend cherilyn wanted her to sleepover at her house!! then the next day we were supposed to go to the beach together and she never showed up at my house and when i phoned her that night and asked why she didnt show up she said she decided to go to the movies with the same friend instead... now this month we were supposed to go to the stampede in my city together and she hadnt talked to me for 6 days so today i phoned her and she finally picked up and i asked her if we were still going to the stampede together and she said idk so im like what do you mean and she said well katie wants me to go with her also . and im like so your gonna blow off your best friend so you can go with katie? :( and she said well i went with you last year and maybe your not my best friend anymore ... im so confused!!!