Call it Jon & Kate Plus One Angry Brother.
In a new interview with E! News, Jason claims that his Reading, Pa., home was the rendezvous spot of choice for his 23-year-old sister and the 32-year-old Gosselin, both of whom have emphatically denied that their relationship has gone beyond the realm of platonic.
The elder Hummel is also fuming over his sister's claims that he has been making up salacious details after her headline-grabbing public outing with Gosselin.
"I am not a liar," Jason insists. "The rumors are true. It feels good to let people know that I am not the liar."
And despite the ramped-up tabloid attention and continued production of the Gosselins' TLC show, Jason says: "Personally, I do think they're going to continue seeing each other. I think they think they can get away with it.
"I hope she is not in love with him."
He also offers more details of the purported affair.