Talking to the How to Life podcast, the 32-year-old admitted that his insecurities got the best of him, despite his efforts to brush it off and telling Angie that it was okay.
"She really cared for Timm. They were kind of messaging a little bit afterwards. I was trying to play it cool, like 'it's fine, it's all good'," he said.
"I was trying to be nice and I was trying to do the right thing... And then more and more, her and Timm messaging each other, it just started to really eat me away."
Carlin and Angie called it quits back in July this year after ten months of dating.
He then brought up the connection that Angie had with Dancing With The Stars partner Julian Caillon.
"Then she goes on to the next show, Dancing with the Stars, with this hot Italian dude and I'm like, 'Oh man, this is not easy. He's a good looking dude,' he said."
Her stint on the competitive show proved to also cause some distance between the two as most of her time was taken up by training.
"She would train for five hours a day with this guy, five days a week, and then fly to Melbourne for four days," he revealed.
Carlin then opened up about how Angie messaging Timm combined with having to re-watch The Bachelorette as it aired on TV, caused his self-esteem to hit an all-time-low.
"So I'm like, 'You get to spend so much more time with this guy and I'm still feeling pretty shit about having just watched you mack on with all these other dudes... I wasn't ready for it. So we had a pretty difficult run," he said.
And while the personal trainer reaffirmed that it was in no way Angie's fault, he did tell the podcast that he was addressing his personal issues with therapy.