In the new issue of Us Weekly (on newsstands Wednesday, 5/6), five people close to the situation - including two relatives of the other woman - confirm that Jon & Kate Plus 8 dad Jon Gosselin, 32, has been having an affair with third grade school teacher Deanna Hummel.
The most explosive blow-by-blow details are revealed by Deanna's older brother - and roommate - Jason, who tells Us Weekly that he is speaking out now to set the record straight and to protect his naive sister.
"She's a nice girl, not a homewrecker," Jason tells Us Weekly. "He is a bad liar. This isn't healthy for her. But she is refusing to help herself, so here I am trying to help her myself. I hope this clears the air."
After Jon and Deanna met in mid-January at Chill Lounge in Reading, Pennsylvania (they sent each other $3 shots), Jason says Jon -- who has twins, 8, and sextuplets, 5 -- began relentlessly pursuing his sister. By mid-February, he was coming over to their Reading house.
On April 26 - while his wife Kate was traveling - Jon had Deanna over to sunbathe in his family's front lawn (see photo, top). This was just seven days after they had first been photographed together at Legends Lounge at 2 a.m. in pictures that show he is not wearing his wedding band.
At the Hummel house, Jason says Deanna and Jon would "pretty much stay locked away like two teenagers. It was weird. He's a grown man."
He also adds, "A lot of the time, it was pretty, um, gross listening to her, you know, um — how do I say this? The walls are thin. Let’s just say that. I mean, no one wants to hear his sister having sex, let alone with a married dude who's, like, almost twice her age and who has eight kids and a maybe-crazy wife. Ick. Nast."
Jon and Kate Plus 8: Season 5--is due to air May 25 on TLC.
Previews on TLC promoting Summer Fun show the season opener featuring "Emeril" visiting the Gosselin Manor and cooking with Kate, Jon and the kids.
SEE A VIDEO OF JON GOSSELIN SNEAKING OUT OF DEANNA HUMMEL'S HOUSE