How can one deal with a wife who is excessively suspicious, searches the phone, and accuses her husband of betrayal, causing him psychological torment and fear for the future of his marriage and his daughter?

The husband is advised to be patient, as what the wife does stems from her love and jealousy. Trust can be built through faith, awareness of Allah's watchfulness, and the wife sharing in the husband's concerns and news. The wife is advised to fear Allah and to be good to her husband, and not to ruin her home with jealousy that spoils the purity of love. She should strengthen her trust in her husband and remember that the default is to think well of a Muslim, in accordance with the Almighty's saying: "O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin. And do not spy or backbite each other. Would one of you like to eat the flesh of his brother when dead? You would detest it. And fear Allah; indeed, Allah is Accepting of repentance and Merciful."