What's a modern equivalent of "fie on thee"?
Solution 1:
According to Etymology online, fie (late 13c) was
a general sound of disgust that seems to have developed independently in many languages.
So, today, it seems a good correlation would be the tsk-tsk sound one makes with their tongue on hearing something they disapprove of. (Maybe the Brits say Tut!, but I don't know. I think of Winnie the Pooh when I hear that.)
Another exclamation still used for the same purpose is
pshaw (interj.) exclamation of contempt or rejection, by 1670s.
I've heard people "say" pffft! or hmmph! for the same reason.