I generally prefer to be notified, particularly if the edits are significant and/or change the theme of the story. That being said, that has never happened to me.

It's your publication, you set the rules as you see fit. People can either like it or lump it. And to go on a long vitriolic rant about you having made edits (as an editor), well that's simply childish, at least to me.

Honestly, if it were me I'd have done one of two things, rejected the piece and saved myself the trouble, or, if I felt it really could be saved, sent back a note just saying, it needs significant reworking, a couple of bullet points about what that might be and leave it with them to do as they wish. Just my 2 cents.