Emily Maynard's family vacation with fiance Jef Holm ended in tears after he caught the Bachelorette starlet cheating. 

The 26-year-old stay-at-home mom and her daughter, Ricki, 7, joined Holm's extended family for vacation at a beach house in Pawleys, Island, South Carolina. On August 19, Holm, a 28-year-old water-company exec, was blindsided when he found explicit text messages and photos to and from another man on his bride-to-be's phone -- and the new issue of Us Weekly has the exclusive details of their explosive fight. 

After reading the story in Us on Wednesday, Holm's brother, Mike Holm, confirmed it was true.

"I can tell you that it's all 100% true. I was there and I heard the fight and watched the whole thing go down, Emily leaving and everything," Mike told Us exclusively. "I love my brother very much and, like the rest of our family, I just want him to be happy."

But his brother also hopes the two will stay together. (The couple got engaged in May, which was taped for the finale of The Bachelorette.)

"We all love Emily, too. Mistakes happen, we all get that," he explained. "I hope they can work it all out, but as far as your story goes, it's all true."

For all the details on Maynard's shocking betrayal, pick up the new issue of Us Weekly, on stands Friday.