I ruptured my left ovarian cyst how long does this severe pain suppose to last?

Really varies: It depends upon whether or not the cyst was simple/fluid filled versus blood filled and how big it was. It is also important to check to be sure there is no ongoing bleeding from a blood filled cyst and to be sure the cyst was not the result of an infection/abscess. All other things being equal it should be improving over a week or two at most. See your doctor again if worsening.