Kate Gosselin Says Her Kids Are ‘Sad’ About the ‘New Daddy’ Jon Has Become Since the Split

Kate Gosselin knows firsthand that divorce isn’t easy, especially on children.

The mother of eight is exclusively opening up to PEOPLE about her past relationship with ex-husband Jon, 39, and how their eight kids handled the big shift in their family’s dynamic since the couple’s 2009 split.

“I look at honestly as two different people — back in the day, he could change diapers faster than anyone, he was there, he was involved, ever-present, very involved, the kids remember him that way, as well,” Kate, 41, reveals in this week’s issue.

Then the former reality star couple’s marriage crumbled at the height of their success as reality stars on TLC’s Jon & Kate Plus 8.

“I can remember those good days without any jaded ugliness,” she continues. “The kids and I remember those days because they are their memories, too. The kids have coined it ‘Old Daddy’ and ‘New Daddy.’ It’s how they’ve been able to deal with it. very sad, more than angry, in the end.”

For more updates on the Kate Gosselin and her eight, pick up this week’s issue of PEOPLE, on newsstands now

In the decade since Kate and her brood stepped in front of cameras, she’s seen just how much her eight children have all grown — not just physically, but mentally and emotionally.

“I don’t see it in terms of their physical changes, but I do see it in terms of their maturity — the ways they’ll talk to me, the things they are capable of and their abilities now,” she explained. “I’m having a conversation with Mady and Cara now, and they’re almost eye-level with me, for starters, and that’s mind-blowing.”

Kate Plus 8 returns Tuesday at 10 p.m. ET on TLC.