OP, why aren't you asking DL to be re-routed onto VS metal where PE is available? Your situation sucks but you seem to just be pissed off and not taking steps to mitigate. This is not going to help you!

You cannot demand or assume you will get an upgrade to business, even though others may be getting this. Perhaps the J cabin is full already on your date of travel?

Apart from cancelling the booking, this seems to be the best options to me. Find a routing you want and tell them to change your booking.