I don't mean to defend them because this move is stupid, but to help you get this back in control: you can go you your about page and set the @facebook email to be hidden. I had done this in the past and they didn't touch it.
It doesn't seem to be clear, as I write this, exactly what is going on there and how much is completely automatic/without consent vs. how much was "expected" behaviour. It's pretty clear that a lot of people aren't happy about it regardless, though. Even if some contact originally got onto your phone via integration with a third party service, that could have been years ago. If you weren't aware that the contact was only remaining there/unmodified because the third party chose to leave it that way, it's understandable that you might be upset if that changed without warning after a long time.