Perhaps you and your family would be more comfortable with the children attending a faith based school, taught by nuns?
As a child, as a parent, and as a member of the equivalent of a school's Board of Governors, I never expected teachers to 'be above all that', to not take an interest in their body and their relationships. They're human beings with lives outside the school gates, and like everybody else, their body is their own, not community property.
If my children or partner had come home gossiping about a teacher's body in such a fashion, they'd have got short shrift, reminded of the above, and that they have absolutely no right to police a person's body, including their teacher's.
They're mammary glands. So, they have increased in size. What of it? I'm sure the nipples are covered. I'm sure she can still teach just as effectively as she could before. Her boob size says nothing about her, and other peoples inability to refrain from gossip and commentary says much about them, and none of it favourable.
And just like that teacher's boob size, if people wish to continue this thread and comment upon it, there ain't a thing you can do about it.