'90 Day Fiancé': Alina Hopes This Lie Doesn't Ruin Her Relationship With Caleb (Exclusive)

A big secret is hanging over Alina's head when it comes to her relationship with Caleb.

Alina is wondering how long she can keep a secret from Caleb in this exclusive clip from Sunday's new episode of 90 Day Fiancé: Before the 90 Days. In the clip, Alina talks to her best friend, Elijah, and worries that telling Caleb the truth about her past relationship will ruin their intensifying romance.

Alina and Caleb first connected when they were 15 years old on social media but lost touch for 13 years. They then amazingly matched on a dating app, which reignited their feelings for one another. The two traveled to Turkey this season to meet in person to see if their online connection translated to real life, and so far it has, with the two getting intimate during last week's episode. In this exclusive clip, Alina tells Elijah she's definitely getting more attached to Caleb but that she hasn't told him about living with her ex.

"My ex and I, we were still together at the time that things were getting serious with Caleb and I. We actually lived together and I hid this fact from Caleb," she tells cameras. "I didn't tell Caleb because I didn't want him to back off so I ended up just not telling him at all."

When Elijah threatens to tell Caleb himself since Alina is too scared to, she agrees that it needs to come from her.

"I have to come clean to Caleb about my past because I don't feel comfortable pushing him for answers about our future while I'm still holding on to this secret," she says. "He's a guy who always tries to tell the truth so I really don't know how he's going to react to hearing that I lied to him. So I just hope that it's not going to screw all the things up."

New episodes of 90 Day Fiancé: Before the 90 Days air on Sundays at 8 p.m. ET/PT on TLC.