Where in the poem "My Last Duchess" does it clearly state that the Duke is a very controlling men?
Will't please you sit and look at her? I said
"Fra Pandolf" by design, for never read
Strangers like you that pictured countenance,
The depth and passion of its earnest glance,
But to myself they turned (since none puts by
The curtain I have drawn for you, but I)
... Sir, 'twas not
Her husband's presence only, called that spot
Of joy into the Duchess' cheek;
In these lines the Duke is "allowing" his visitor to view his former wife...to see her as he would show any piece of property. We can read between the lines that he expects things to be only for him--for "her husband's presence only" that she show any joy and enjoyment. This is absolute evidence of control. However, if this does not convince you, try these lines:
Never to stoop... but who passed without
Much the same smile? This grew; I gave
Then all smiles stopped together.
The Duke here is telling us that he thought his former wife should know how to treat him and only him. That he never would "stoop" so low as to instruct her or give her any guidance whatsoever as to what he expected. He simply "gives commands" and her smiles to everyone and everything stopped altogether. Now, she just hangs upon the wall "looking as if alive" so we get it that he ordered her dead. That is the epitome of "control freak."