On Wednesday night's episode (3 August) of the ITVBe show, Kate told the girls she'd heard Dan had bedded another woman on a night out, admitting: "It sets me back a bit."
Kate and Dan split following a holiday to Mexico in May, saying the spark had gone from their relationship. Although they did sleep together in Majorca at the start of the series.
Chatting to the girls during a day at the park, Kate discussed how she was coping with the split, saying she's fine if what Dan gets up to in his private life remains a secret to her, but less fine when she sees things posted on social media.
"I'm fine when I don't see Dan but when I see things on social media it sets me back a bit," she said. "When I don't hear or see anything I'm fine, but when it's in my face...
"Someone Amber knows told her Dan slept with this girl at an after-party and I did ask Dan but he said it's not true. They always deny it. Deny until you die. Sleep with who you want but don't tell me and then I don't have to deal with it."
Dan, however, later told the boys the suggestion was "b*llocks", saying: "Listen, me and Gatsby after Faces went back to an after-party with girls we've known a long time. That's it. I understand Kate is questioning it. If it was the other way around, because it's quite fresh, it would hurt me."
"She don't believe me," he added. "It's definitely changed things. Whereas before we were speaking every day, still on a friend basis, since this thing got brought up we haven't really been speaking and we're definitely distanced a lot more. It's holding us back a bit. I am still thinking about Kate, do you know what I mean?"
Kate was less than impressed later on to find Dan and new flatmate James 'Arg' Argent had a condom jar in their new apartment, saying: "I just feel like it's disgusting. What? You're going to sleep with loads of five out of tens? How romantic."
She added that co-star Jon Clark was going to be unfollowed on Twitter if he didn't stop posting about Dan's romantic exploits. "It's just winding me up. Let them do what they want to do, but don't write it on social media," she said. "Jon Clark is tweeting things like, 'Get at me if you want a bit of Dan and Arg' which is fine, they can do what they want, but if he carries on with these tweets he's going to have an unfollow."
TOWIE continues Sunday at 10pm on ITVBe.
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