Hi There, I Live In Montreal, Canada And Had Unprotected

hi there, i live in montreal, canada and had unprotected sex on tuesday night (october 27th). by my calculation of my cycle that was exactly when i was ovulating. i am considering the "morning after" pill. i know it is too late for plan b, but ella supposedly works for 5 days. is it true that if i already ovulated and the egg has been fertilized, ella will do nothing? it's just in case, after 4 days, the sperm remains alive and might fertilize the egg in the coming day, right?