As Robert prepared to marry Chrissie, Aaron lured him to Wylie's Farm to try and convince him to call wedding off.
But Katie caught them in the act. She said: "Well, isn't this a surprise."
A desperate Robert tried to get her to delete the picture, insisting it was nothing more than a goodbye kiss.
Robert attempted to bribe Katie, but she told him she would expose his affair with Aaron.
Losing his cool, Robert grabbed Katie and threw her to the ground. Shockingly, the floor collapsed, sending Katie falling to her death.
Returning to the matter in hand, Robert managed to delete the picture. He then called Aaron back, where they both decided not to call the police.
Danny Miller, who plays Aaron, recently admitted that the plan got way out of hand.
Speaking to Digital Spy, he said: "If he'd known it was going to end that way, he'd never have left Robert and Katie alone at the farm.
"Aaron is asking lots of questions about what happened because he is so shellshocked. Robert gives a version of what happened, but as far as Aaron is concerned, he could be saying anything.
"Afterwards, you'll see that Aaron doesn't know how to deal with this situation because Robert quite manipulatively starts trying to put this on him."
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