This week, Briana DeJesus announced her engagement to Javi Gonzalez.

The announcement was a surprise for many fans.

But one of the replies was downright shocking to longtime Teen Mom 2 viewers.

Kailyn Lowry commented ... to offer her sincere congratulations. What's going on?

TikTok isn't the most common platform for announcing an engagement.

But that was the venue that Briana DeJesus chose on Monday to share her happy news.

Briana shared a montage of photos and videos of herself and her now-fiance Javi Gonzalez.

The video montage was set to the song, "perfect Duet," by Ed Sheeran and Beyonce.

Many fans were excited and offered their congratulations.

But it was Kail's comment that blew people away.

"This popped up on my page!" Kailyn wrote in a comment.

"OMG, congrats!" she announced.

Alongside her comment, Kail included a party emoji and a champagne popping emoji.

That is surprisingly amicable and even friendly ... and it gets weirder.

Briana replied to Kailyn with a comment of her own.

She wrote "Thank you" with a red heart emoji. What is going on???

Fans had already been shouting their congratulations from the rooftops.

After all, this was huge news for Briana, and many people have been rooting for her to find happiness.

But seeing the exchange with her and Kail was nothing short of inspirationa.

Fan comments surged under the TikTok post.

Many were praising the "growth" that the two women had displayed.

After all, they are former rivals -- and arguably former enemies.

“Growth baby girl love it !!!" raved one commenter.

That same comment continued: "Grown women stuff love both of you ladies.”

Another praised Kailyn, writing: “Well thats super sweet of you.”

“I love seeing this!” another of Briana's many followers told Kailyn.

“This is the definition of a mature woman!" appraised another.

That same commenter added: "We love to see this Kail.”

As we all remember so vividly, Briana and Kailyn's tense interpersonal history goes back years.

Briana first joined the Teen Mom 2 cast in 2017.

The strong feelings of mutual dislike flared up very quickly.

Kailyn divorced Javi Marroquin, though they would always remain linked by their shared child.

But they also remained linked through the show.

And then, of course, Javi began dating Briana.

Understandably, this created a major rift between the women.

They have taken turns with jabs at each other.

Many of these not-so-veiled insults have involved stories about spending 

In 2018, things got even worse at the Teen Mom 2 Reunion.

There, Briana accused Kailyn of both texting and harassing her during her brief relationship with Javi Marroquin.

As the women came face to face, emotions flared -- and things got physical.

Even just last week, Briana stirred the pot.

She shared an article about Kailyn and Devoin Austin.

The insinuation was that Kailyn was boning Devoin.

The truth of the matter was that Kaily had invited Devoin as a guest on her podcast.

The goal was to lend him a platform to speak about himself, his time on the show, and Briana's family.

But Briana has shared clickbait that suggested, to those too lazy to read the actual articles, that Kail and Devoin are boning.

Now, they seem to have struck a truce -- or at least, a ceasefire.

How long it can last, no one knows.

We all like it when there's peace, but reality stars know that feuds are a great way to stay relevant ... so how long until someone picks a fight again?