Wa `alaykum As-Salamu wa Rahmatullahi wa Barakatuh

I’m sorry to hear what happened. Your husband’s pronouncement of one divorce statement over the phone counts, even though it was prohibited for him to say this during your period. However, this only counts as one pronouncement of divorce. Your husband may retract this divorce by saying “I retract my divorce” as long as it is done before you have completed three menstrual cycles [about three months from the time of pronouncement].

Once he has retracted, you both remain married as normal. If he pronounces divorce like this again, he may retract once more. After that, there is no retraction after the third pronouncement of divorce, and the two of you must be fully divorced and separated. Allah says, “Divorce is twice…” (Al-Baqarah 2:2290

Almighty Allah knows best.