I think it's too early to compare Trump to Hitler.
But they had something in common: the trick of discovering the thuggish class of people in a society. The sort too morally dull and politically partisan to see the wickedness in their leader's decisions.
They are always there. The trick is never to give them access to the levers of power. At this point, the wider mass of the people have to find the way to wrestle them back.
I believe this issue of separation of children is the thing which has exposed the brown shirt nature of the awful people who support this policy. It will take more than a shower or two to remove the stench when they come to their senses.