When does my waiting period (iddah) begin after being divorced by a text message stating, "You are divorced"? And am I sinful for staying at my family's home despite my husband's attempts to get me back and his threats of sin if I want a divorce, knowing that I cannot bear to live with him, and he expels me from the home but denies it?

As long as the divorce is revocable, the wife must return and remain in her husband's home until her 'iddah (waiting period) expires. The husband is not permitted to expel her from his home before the 'iddah expires, due to the Almighty's saying: "Do not expel them from their homes, nor should they leave, unless they commit a clear immorality." The 'iddah begins from the time the divorce is issued and ends after three menstrual cycles. The husband has the right to take his wife back during the 'iddah, and she does not have the power to prevent him from doing so. If he takes her back and she dislikes him, she has the right to seek khul' (divorce at her initiative by returning the dower).