I hear your cry, and I grieve with you for your daughter's state. You speak of spiritual attacks, and truly the enemy prowls, seeking to devour souls through lawless unions. Yet take heed: while you rightly discern the evil, do not let the same enemy gain a foothold in your own heart through bitterness, wrath, or a spirit of judgment. For we are members one of another, and if love leave us, the whole body is rent in pieces. Your daughter, though straying, remains your own flesh; owe her the debt of love, even when love is hard. Pray, then, and entreat the Lord with tears, but do not hate the man nor his mother, lest you darken your own soul while seeking to rescue hers.
Consider: God often permits such trials not to destroy us, but to teach us to despise the world and cling to Him alone. He did not promise the apostles deliverance from death, but gave them strength to overcome the fear of death. So too, He may not snatch your daughter from her sin in an instant, but He can work in her a true turning, if you persevere in faith. Remember Jonah: how did the whale's belly contain him without perishing? To reason it is impossible, but by faith it is exceedingly credible. So now, though your daughter seems swallowed by a living hell of isolation and manipulation, the Lord who commanded the beast can command her deliverance. Only let her cry out from that depths, and she shall be heard. Your prayers for her can be that very cry.
But let your prayers be joined with humility. Have no high thoughts, as if your own righteousness or your family's goodness merited God's favor. What do we have that we have not received? If you boast in your own virtue, you shut out grace. Even this spiritual warfare you describe, speak of it with fear: "Who is pure from this passion? Except indeed I am but conjecturing the case of others from myself." Let your plea be the publican's, not the Pharisee's.
Teach your daughter, when you have occasion, that the pleasure of sin is fleeting. Luxury indeed gives a show of sweetness, but after the table is removed, the belly curses the man, bringing only drowsiness, ache, and a sleep like death. Her present arrangement offers no true covering; it is not marriage but a fellowship of thieves, stealing her peace and her future. Yet do not harangue her with scolding, this often hardens. Instead, let her see in you a peace that passes understanding, and a life not riveted to earthly things. When God sees that we set a higher value on spiritual realities, then He often bestows carnal blessings. Seek first the kingdom, and all else will be added.
As for the young man's mother, you name her words curses and witchcraft. Be careful. Our battle is not against flesh and blood, but against principalities. It may be that she is but a blind instrument; pray that she, too, may be delivered from pride and manipulation. But if you fix your gaze on her schemes, you will be consumed with enmity. Instead, leave her to God: "Beware of false prophets," yes, but He will frustrate every plan not of His planting. Your task is to love your daughter without condition, so that she may see the difference between the family bought by Christ's blood and the one offering worldly approval.
Take heart: the promise of sonship is not through natural descent but through faith. Your daughter's true lineage is from above, and you did not give birth to her spirit, but God did. Commend her, then, into the hands of Him who is able to bring her back from the dead, morally and spiritually. Give alms for her sake; increase the fruits of righteousness. Let your life be a living homily, for a silent example often pierces deeper than words. And when you pray, plead the blood of Jesus, for no weapon formed against you shall prosper.
Restore unity within your household by that same humility. Do not speak of your son's ### as a burden; indeed he is fearfully and wonderfully made. Treat him with such honor that his siblings may learn compassion not from precept but from your own tender care. If any word of division is spoken, let it die in your silence, for love covers a multitude of sins.
Hold fast, then, and do not despair. The God who called Abraham from Ur can call your daughter from her far country. Only believe, only love, only pray without ceasing. And may the Lord grant her eyes to see that this man is no husband, no provider, no spiritual covering, only a snare, and may He restore her to the family, not as a prodigal shamed, but as one found, robed, and feasted. Let us dwell on these things, and not on the darkness, for He who is in you is greater than he who is in the world.