Does a return [to the marital state] take place after a husband divorces his wife while angry via WhatsApp, knowing that the wife wishes to return, and what are the implications of that?

The ruling on explicitly writing a divorce statement with the intention of threatening is a matter of scholarly disagreement. Some scholars consider it to effect a divorce, while others do not, because they deem it an implied divorce (kinayah) that requires intention. This latter view is the one given fatwa (considered authoritative). If the divorce is effected, the wife becomes irrevocably separated upon the expiry of her 'iddah (waiting period) by giving birth to her child. You cannot take her back except with a new marriage contract. A legal contract, with the presence of two witnesses, is sufficient, and a divorce certificate is not required. However, if the divorce is not effected due to the absence of the intention to divorce, then the wife remains under your marital bond and returns to her home without needing a new contract. The wife must treat her husband with kindness and obey him in what is right. Her obedience to him takes precedence over her obedience to her parents or brother. If her brother incites her to disobey you, you have the right to prevent her from visiting him and to prevent him from visiting her. There is no need to refer the matter to the judiciary unless it is necessary to settle a dispute.