What is the ruling on divorcing one's wife during her menstrual period while angry, and how can she be taken back? What is the last time for that, and is the upcoming menstrual period considered the third and final one, or the one after it?

Divorcing a menstruating woman is forbidden and valid according to most scholars. If the divorce is less than three pronouncements, you may take her back as long as she is within her waiting period (iddah). The waiting period is three menstrual cycles, and the cycle in which the divorce occurred is not counted. If the wife becomes pure from the menstruation during which she was divorced, and then menstruates again, this is considered the first menstrual cycle of the iddah. It is recommended for one who divorces his wife while she is menstruating to take her back, then leave her until she becomes pure, and then either divorce her or keep her. Taking her back is obligatory according to the Hanafis and Malikis if a man divorces his wife with a single pronouncement while she is menstruating, based on the hadith of Ibn Umar regarding this matter. It is sunnah according to the Shafi'is and Hanbalis.