This is your own fantasy. It is not what Catholics believe, and it is not what they mean by the title "Mother of God."
As long as you keep railing against something Catholics don't believe, they will just laugh at you.
The title "Mother of God" means that Mary BEGAN to be the mother of Jesus Christ, the Son of God, when he BEGAN to be God Incarnate, in her womb.
So you see, the title "Mother of God" does NOT mean or imply that Mary pre-existed God, and does NOT mean or imply that God had a beginning.
As long as you insist on distorting the meaning of "Mother of God," and railing against your fantasy version, Catholics will continue to laugh at you.
I forget the Catholic need to redefine words to fit their world.