"This is going to be my final season, my final reunion," the MTV star says to her castmates in a sneak peek

Chelsea Houska's time on Teen Mom 2 has officially come to an end.

In PEOPLE's exclusive sneak peek at part one of the season 10 reunion, Houska — who confirmed her exit in November — reveals to costars Leah Messer, Briana DeJesus, Kailyn Lowry and Jade Cline that she won't be returning to the MTV reality show.

"So this is going to be my final season, my final reunion," Houska, 29, says during the virtual taping. "And it is definitely bittersweet. And it's weird that the last one is here like this, and we're not all together."

Co-host Dr. Drew, who admits he is "both pissed and sad" about her departure, then asks about Houska's decision to bow out.

"I feel like, just watching this last season, I was getting a bad feeling in my stomach. It just feels like it's just time to close the chapter. And I'm almost 30, I'm having my fourth baby — it just feels like the right time," explains Houska, who is expecting her third child, a baby girl, with husband Cole DeBoer. (She's also mom to daughter Aubree with ex-boyfriend Adam Lind.)

Hearing the news, DeJesus, 26, says "more power to you. Good luck on your journey with you and your family. I wish you nothing but the best."

Chelsea Houska and the Teen Mom 2 cast
Teen Mom 2 reunion
| Credit: mtv

Messer, 28, says she "wasn't necessarily expecting" Houska's departure. "It's sad. It's definitely bittersweet, but I think that Chelsea and her family get to make the best decision for their family at the end of the day and I wish them nothing but the best."

As for 23-year-old Cline, she is "really surprised. Honestly, I didn't like, expect it, especially since she's having a new baby and stuff. It seemed like there was a lot of stuff going on, but I totally understand wanting to step back from the reality TV world."

For Lowry, 28, her longtime costar's exit didn't come as a huge surprise. "I'm not entirely shocked, just because I do talk to Chelsea pretty often, so we've had conversations here and there. But, you know, I definitely told Chelsea, 'This is obviously the right decision for you if you feel like there's a weight lifted off your shoulders.'"

And while she admits that it is "going to be a little bit weird of a dynamic without her, because we've been doing this together for 10 years," Lowry is excited to see what opportunities her friend will explore "once she moves on."

Houska first made her MTV debut on 16 and Pregnant in 2009. She went on to join Teen Mom 2 and has been a part of the cast since its inception in 2011.

Chelsea Houska and the Teen Mom 2 cast
Chelsea Houska
| Credit: mtv

On Teen Mom 2, fans watched as Houska met DeBoer in 2014. The two are now married and share daughter Layne, 2, and son Watson, 3. DeBoer also helps raise Aubree, 11.

In an Instagram post on Nov. 10, Houska confirmed her exit from the show, saying she came to the decision with DeBoer.

"MTV's Teen Mom 2 has been a big part of my life for almost 11 years," she said. "After much thought and discussion with my family and friends, Cole and I have decided that this season will be our last. We are forever thankful to MTV and our crew, who are like family to us. We're parting on the best of terms and will stay in touch long after this."

Part one of the Teen Mom 2 reunion airs Tuesday at 8 p.m. ET on MTV.