Scheana Shay just dropped a bomb — she says hubby Brock Davies cheated while she was pregnant with their baby, Summer Moon.

In her upcoming memoir, “My Good Side,” the “Vanderpump Rules” star reveals she was frozen in shock when Brock confessed he cheated with a woman from his gym back in 2021 — while they were living in San Diego during the pandemic and Scheana was pregnant.

Scheana says she spent months battling anxiety, convincing herself Brock wasn’t like Tom Sandoval — who’d hit headlines for cheating on Ariana Madix at the time — but turns out, he was exactly that guy.

Scheana admits she totally lost it — she slapped Brock and chucked a Rubik’s Cube at him. He even handed her a letter he’d written a year earlier detailing the whole affair — time, place, how many times. Her response? Burn it. Immediately!