Last night, viewers saw Kat name Derek as her mystery Branning man in a packed Queen Vic after her husband Alfie demanded the truth from her.
Tonight's episode of the BBC soap sees Alfie (Shane Richie) throw everyone out of The Vic following the huge revelation, but it's not long until Derek returns to speak to him.
Rather than helping the situation, Derek (Jamie Foreman) maliciously makes things worse - which provokes a furious response from Alfie as he punches the Albert Square villain and warns him never to step foot in the pub again.
As Derek leaves, Alfie's world begins to crumble with only Roxy Mitchell (Rita Simons) there to support him…
EastEnders airs these scenes tonight at 8pm on BBC One.