Do the statement or don't, but the EA is on to a loser. It doesn't matter how genuine or proceedable you were, the sale fell through and so there's no commission payable. It would be a different matter if the seller was intending to go ahead with selling to NB and planned to cut the EA out of the deal, but you say the EA is "100% sure" that NB never really existed so it can't be that. The days of fixed-term contracts with EAs are a thing of the past as far as I can see (I am selling atm) so I imagine they're now free to sell via a new agent or none, though whether they get the higher price is another matter (and the market isn't going to keep climbing for much longer, so they're gambling imho). The EA is entitled to block them from using his pictures, though it's hard to see why they wouldn't just replace them with some of their own rather than paying him anything for them. I'm sure it's galling to have lost his commission on the sale, but I'm surprised the EA is taking all this so personally - you would think this stuff happens all the time tbh.
Good luck finding another house, OP. And there's always another house.