Whether you understand my situation or not will not change the fact that I love my family and will continue to pray for my grandchildren. God knows what's on my heart and knows the situation and only he can be the judge of it and do what he sees should be done
I freely admit I do not understand your situation and you should pray always for your family.
However which is more important to you and God. That you have a man who has turned away from God in your grandchildren lives or that you lead Your daughter to repentance and humbleness before God?
From your own words you show you have some misconceptions..,a good father would love the mother of his children and be married to her as God intended...he was not a good father by God's standards. Even if he met the outward worldly appearance of one.
It is arrogance and pride of your daughter's part to think herself perfect and blame God for her break up. Why does she not blame her cheating husband and his sinful nature? Why does she value a relationship with this man more than a relationship with God?
Why would God answer the prayers of someone who is still in rebellion?
If you truly want to help your grandkids, teach them that having God's love is enough and it's their fathers lost because when they are grown he will regret missing these precious moments in their lives. Have them forgive and pray for him. Yes they may be angry, but if they have God's love in their hearts then they will not be lacking. They need to learn to forgive the hurts and grow and heal.
Perhaps by their love they can lead both of their parents back to God. For childlike faith moves even the,most harden heart.
I will pray that God pours forth His love In your life and the lives of your grandchildren so that you may all shine a light into the lives of those around you. May God bless and keep you.