What is it, Michael?” She broke off crossly, for Michael had grasped her skirt in his hands and was shaking her.
“Did she say she’d come back?” he cried, nearly knocking his Mother over. “Tell me — did she?”
“You will not behave like a Red Indian Michael,” she said, loosening his hold.
...
“You are a very cruel woman,” said Michael, clenching his fist as though at any minute he would have to strike her.
Mary Poppins
________________________________________________________________
Michael could not possibly strike his mother...
Therefore "have to" can't be neither "must to" nor "ought to", and "would" can't be ""will" in the past".
I don't understand that "would have to" then
“Did she say she’d come back?” he cried, nearly knocking his Mother over. “Tell me — did she?”
“You will not behave like a Red Indian Michael,” she said, loosening his hold.
...
“You are a very cruel woman,” said Michael, clenching his fist as though at any minute he would have to strike her.
Mary Poppins
________________________________________________________________
Michael could not possibly strike his mother...
Therefore "have to" can't be neither "must to" nor "ought to", and "would" can't be ""will" in the past".
I don't understand that "would have to" then