Teen Mom's Catelynn Lowell snubs cast reunion after slamming 'heartless' sister Sarah

Teen Mom star Catelynn Lowell skipped a cast reunion at Briana DeJesus' house after taking aim at her "heartless" and "cruel" sister Sarah.

The reality star, 30, took to her social media for a fiery rant against her sibling following an alleged TikTok video in which Sarah 'spread lies' about her 'PTSD and trauma'.

Co-stars at the boozy bash included Jade Cline and her fiancé Sean Austin, Cheyenne Floyd and her husband Zach Davis, Briana's ex Devoin Austin and her sister Brittany DeJesus.

Snubbing the get-together, Catelynn went live on her Instagram to address claims made in Sarah's video – launching into a scathing rant.

Catelynn hit out at her 'heartless' sister Sarah (MTV)

"So I have a sister named Sarah, she went on TikTok yesterday and posted a video saying many things," she said while kicking off the stream.

"She went on TikTok yesterday and decided to make a video saying that nobody knows my real truth, that my PTSD and trauma are all lies.

"She basically disregarded me having PTSD and trauma and said that: 'We are only four years different so if Catelynn has all this trauma, why don't I have any trauma?'

"The b*tch does not know she has trauma because she has never worked on her s**t."

The Teen Mom cast reunited at Briana's house (_brianadejesus/Instagram)

Catelynn added: "She tries to act like, you know, everything is fake.

"She even said something like 'The reason Catelynn placed her daughter for adoption is because she was afraid Tyler was going to leave her.'

"It's not accurate at all, I wasn't forced to do the adoption, I made the f**king decision my damn self, nobody forced me at all."

Catelynn's husband Tyler Baltierra joined in the conversation, calling his spouse's family "toxic and miserable".

Catelynn was noticeably absent from the get-together (Patrick McMullan via Getty Images)

Her husband Tyler has since released a statement too (Getty Images)

In a lengthy statement he said: "The audacity of some of my in laws is astounding! (however not surprising unfortunately). Especially after everything my wife has done for them.

"I wish I could say that I’m in shock…but I’d be lying.

"My wife has literally done nothing to deserve any of the heartless, cruel, & vulgar comments that her siblings have made about her (both publicly & personally).

"To be honest I don’t even really get mad anymore when this stuff happens (since I’m so used to her family treating her this way)…I just get sad for her."

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