What is the ruling on the quarrel that took place between the spouses via WhatsApp, and does it result in a divorce, knowing that the wife was present in the house upon the husband's return, and that the husband does not know his intention behind the words he uttered?

Your divorce has not occurred due to the words you mentioned in your message to your wife, because you thought she had not returned home. Even if you had uttered an explicit divorce based on this assumption, and then it became clear to you that she had returned to your home, the preponderant opinion is that your divorce would not have occurred in this situation. So, if a divorce is conditioned on a reason, and then that reason is found to be non-existent, the divorce does not occur, whether the reason was mentioned in the wording or not.