Must a divorced woman, immediately after her divorce, wait for three menstrual cycles or three months before remarrying? And is the 'iddah (waiting period) calculated from the time of menstruation or from the time of divorce? And does she need a guardian to marry her if she is 45 years old?

The waiting period (iddah (definition)) for a divorced woman who menstruates is three menstrual cycles, based on the Almighty's saying: "And divorced women shall wait concerning themselves for three courses." If menstruation occurs after the divorce, then your waiting period is three menstrual cycles, and you exit the iddah upon purity from the third menstrual cycle after the divorce. It is not permissible for you to marry until after the completion of the iddah. Marriage is not valid except with the presence of your guardian (wali) or his representative, along with two just witnesses, and a formula indicating the contract.