The answer
In responding to how to be rid of persistent evil thoughts, one of the early fathers Abba Pimen answered: "If a man has on one side of him fire, and on the other side a vessel with water, then if he starts burning from the fire, he takes water from the vessel and extinguishes the fire. Like to this are the evil thoughts, suggested by the enemy of our salvation, which like a spark can enkindle sinful desires within man. It is necessary to put out these sparks with the water, which is prayer and the yearning of the soul for God."Tell your friend to persist in prayers and not entertain these thoughts but try to get rid of them. I also suggest that she gets her priest to pray for her and anoint her with holy oil.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)