Jon Gosselin is firing back.
The former reality star is sounding off after his ex-wife, "Kate Plus 8" star Kate Gosselin, revealed in a tell-all interview that their 12-year-old son, Collin, was away getting help for "special needs." His 15-year-old twin daughters, Mady and Cara, also spoke ill of their estranged father, questioning his intentions.
"I'm very upset," Jon, 39, exclusively tells ET. "I love my children very much. I've always been there for them and I always will be. It's shocking."
In a new interview with People, Kate explains why she enrolled Collin in a program away from home to help cope with his "special needs."
"Collin has special needs," the 41-year-old reality star said. "[There's] a fairly fluid diagnosis of what those needs are, but he needs to learn certain strategies to help him deal with things. This has been a struggle we've had for a very long time, and it's one I've dealt with on my own."
"I've felt very alone in this," Kate added. "By the same token, it's not something that has only impacted me or him -- our entire family has been impacted."
Mady and Cara also addressed their estrangement from their father, with Cara admitting to People, "I wouldn't even know what to say about him."
"He makes it seem like we're being kept from him, which is insane," Mady said, later referencing Jon's ET sit-down from earlier this month. "He should maybe spend some time thinking about why we don't want to see him, and maybe realize that if he ever does want a relationship with us, talking about us on TV is not the way to make that happen."
"He doesn't even know us," Mady added. "How can he dare to talk about us?"
ET exclusively sat down with Jon for a candid interview in August about his estranged family, in which he placed some of the blame on his estrangement from Collin on his ex-wife. He said he hasn't seen Collin in two years.
"It felt like she was segregating me from him," Jon said, claiming that he hasn't seen all eight of his kids together in "three to four years." "I haven't seen him for a really long time."
"Everybody used to come to my house," he continued. "It was great, and then Madelyn and Cara just stopped coming, around 12-13 [years old]. I didn't question it. I was just like, 'Hey, do what you want. Be with your friends,' and then it just became, 'They're not coming.'"