What was the Duchess's fate? Is there evidence in the poem "My Last Duchess" by Robert Browning?

According to the words of the widower Duke, the Duchess,
as lovingly and smiling as he would portray her was also quite salacious and flirty with
people form court. When we get to the point where the Duke explains her demise, we
encounter an enraged and hurt man who may have been cuckolded, and humiliated. In the
Duke's own words, he made the order to kill the
Duchess.

Hence, we read the
words

I gave commands. Then all smiles stopped
altogether.