I feel really left out

well, my best friends friend had a fall out with her best friend so now shes started to hang around with her,im fine with that but today my bff ran away from me pretending it was a joke and in one of our lessons she told me she hated me than 2 days later she said it was a joke, my other closee friend said that I could join her but I dont want to hurt my bffs feelings because I havent told her im feeling left out,
should I just join my other friend ?
please help !

Tell your best friend how you feel, and if she continues to be mean to you than hang out with your other friend. Don't let yourself be dragged through drama when you can have fun with other people! :-)