Prom crisis

so a few months ago, i broke up w/ this girl 'cause she moved across the country. since she was gone, i asked another girl to go to prom with me. however, my old girlfriend just moved back and we are now dating again. prom is next week and i dont know who to go with. do i go with my girlfriend or the girl i asked to prom? also my girlfriend and the other girl really dislike each other