Mary is not the mother of His divinity.
His divinity pre-existed Mary, it did not come into existence when Mary conceived Jesus.
No woman is the mother of what comes from her child’s father. But what comes from the father is part of who the son or daughter is, and the woman is the mother of all that her son or daughter is. In the same way, Mary is the mother of all that Jesus was, though His divinity did not come from her. And what Jesus was included being God.
The following story may show you what I mean.
One day when Jesus was a child, he fell and scraped his knee. Mary came running to him, swooped him up and tended to his wound, saying, “That’s okay, honey, Mom will make it all better.”
One evening a little later, Mary cut her finger while fixing supper. Jesus said, “That’s okay, Mommy, I’ll make it all better.” Mary thought how cute it was that Jesus was imitating her until she saw the serious look on his face, and realized that he was speaking to her as her God.
Now, as far as I know, this never really happened, but it does illustrate the dual nature of Jesus.
He was speaking to her as God when He rebuked her when they found Him in the Temple answering the questions of the priests.
For that that matter, He rebuked her at the wedding at Cana, too.