Is it permissible for a woman who has been revocably divorced (talaq raj'i) and whose husband has abandoned her for six months, and who is living with her sister and brother-in-law, to begin her 'iddah immediately or after a period of time?

A divorced woman observes her iddah (waiting period) in the marital home. The iddah begins from the moment the husband pronounces the divorce. It concludes after three menstrual cycles for a woman who menstruates, or three months for a woman who has reached menopause or is too young to menstruate, or upon childbirth for a pregnant woman. It is not permissible for a divorced woman to leave her home during the iddah, nor is it permissible for her husband to expel her from it, except in cases of necessity or if she commits a clear act of immorality, as Allah Almighty says: "Do not expel them from their homes, nor should they leave, unless they commit a clear immorality." If he divorces her while she is outside her home, she must return to it as soon as she becomes aware of the divorce. It is permissible for her to observe her iddah in her sister's home if the husband prevents her from returning to his home, or if she fears for her safety from him, or if the divorce is irrevocable (bain).