While Jessika had her sights initially set on Cyrell's husband Nic, she turned to fellow newcomer Dan when Nic turned her down.
"I picked that straight away," Billy told 9Honey Celebrity. "She was following him around the room I was onto it before anybody. And Susie said that I was crazy, it was just me being oversensitive. But I was like, 'Hey, I can see, she's making eyes at Daniel something fierce.' I'm like, 'I've seen that before. That ain't just in my mind.' And she's like, 'You're crazy Billy. You read into things too much.'"
Billy explains how he has been in Dan's position before, when a girl is being "just full on".
"Jess had blocked out everybody else in the world and was just focusing in on Dan, and Dan was really contributing," he says. "I've seen that situation before, so I'm quite familiar with that situation, so I could clue into it straight away.
"I didn't know that she'd been in the experiment for a while. I just thought maybe she had had a kind of failed honeymoon and she was ready to really give it her best show with stealing somebody else's man," he added, laughing.
Billy is referring to the fact that he and the other intruders weren't told they were intruders.
"I was like, 'Why are they so excited to see us? That's a bit full on isn't it? Hm. They're very welcoming people'", he says. "It didn't click for me that this was the fourth week of the experiment."
BUT more importantly, poor Mick - Jessika's husband on the show. After the scandalous episode aired, Mick slammed his wife on Instagram before quickly deleting the post.
On a photo of Jess with MAFS bestie Martha Kalifatidis, a fan wrote, "What an a**hole you are! Today's generation! You need to take a good look at yourself!"
Mick reportedly replied to that comment, "boom. Truth bombs."
Watch below... Did MAFS star Billy just confirm he cheated?