What you are describing, the nausea, the depression that drains you of appetite, shows that your own strength is ebbing. When our inner resources run out, it can feel like we have nothing left to bring even to the smallest tasks. And yet, this is often the very place God meets us, because in our weakness His strength is perfected.
Your longing to surrender the situation is right, but I know how hard surrender can be. We wrestle. Like Jacob, we cling to our own schemes, our own timeline, our own vision for how things should unfold. All night long the Lord wrestled with him, hoping he would yield, but it finally took a crippling touch to bring him to that place of blessing. That doesn’t mean God delights in our pain; it means He knows that until our own strength gives out, we will keep relying on it. So do not be afraid when you feel your own grip slipping. That may be the very thing that allows you to truly let go and let God be God.
Even your ex’s father seemed to sense this in his son’s life. He said his son may have to make mistakes before he turns back. It’s excruciating to watch, but sometimes a person’s greatest natural strengths become their biggest spiritual barrier. They trust in their own ability instead of the Lord. You cannot carry the weight of his choices. Your call is to pray, and then entrust him to the One who alone can bring him back. That is part of your surrender too.
As for the depression that overwhelms you, do not simply let it talk you into deeper despair. Learn to speak truth to your own soul. The psalmist did that: “Why are you cast down, O my soul?” He challenged his own downcast heart with the goodness of God. The Lord is your strength, your shield; your heart can trust in Him and be helped. He is a very present help in trouble. So when the feelings of nausea rise and you cannot eat, stop and remind yourself aloud: “God is my refuge and strength. I will not fear, even though my whole world feels shaken.” You are not alone. His hand is holding you, even when your own hands feel too weak to hold on.
Surrender is not a one-time act you check off; it’s a continual turning away from self-reliance and into His arms. The secret of real strength lies in a life separated unto God, committed to Him and leaning on His power rather than your own. As you wait upon the Lord, quietly, expectantly, in prayer and in His Word, He will renew your strength. You will find yourself mounting up on wings like eagles. You will run and not be weary; you will walk and not faint.
May God give you that strength right now. May He bless you with His deep peace as you surrender this man, this relationship, this depression, and your very body into His care. And as you pass through this valley of weeping, may He turn it into a place of springs, so that even here you find refreshment and go from strength to strength.