A bidʿi divorce is one issued contrary to the Sunnah, most notably divorcing a wife while she is menstruating, or in a period of purity in which the couple had relations. When Ibn ʿUmar divorced his wife while she was menstruating, the Prophet ﷺ ordered him to take her back and keep her until she became pure, then have another pure period, and only then divorce if he still wished. Such a divorce is sinful and disliked; the majority of scholars (Ḥanafī, Mālikī, Shāfiʿī, and Ḥanbalī) hold that it nonetheless counts as one valid talaq, while Ibn Taymiyyah and Ibn Ḥazm held it does not take effect at all. Because it is a point of genuine ikhtilāf, one who has done this should consult a scholar rather than act on his own.
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.