"The Fosters" returned Monday with the Season 3B premiere, and the Freeform series, which had been off since the summer, did not waste any time breaking fans' hearts. A.J. (Todd Williamson) decided to skip town with his brother, a second opinion revealed that Stef's (Teri Polo) mammogram did show signs of cancer, and Callie (Maia Mitchell) and Brandon (David Lambert) were still stuck with their big secret. Will things get any better in episode 12, "Mixed Messages"? 

According to the synopsis for episode 12, Brandon is upset when he learns that someone else knows that he slept with Callie. However, someone knowing their secret could cause more problems than just hurt feelings now that the two are officially siblings. Plus, the promo for the episode reveals the pair's past is haunting Callie as she prepares to take her Fost & Found website to the next level.

In episode 11, Callie got an offer for a significant financial investment in the project and the teaser video shows the young girl shooting promotional photos. However, she still has a few reservations.

"I have this huge secret," she tells Brandon. "How am I supposed to let people think that I am some kind of role model?"

"I think you're just afraid," Brandon responds, adding that the secret (and his feelings for her) looms over him as well. "You're holding me back, too."

Watch the promo for "Mixed Messages" below:

Meanwhile, Sharon (guest star Annie Potts) disagrees with how Stef should handle her diagnosis and the tension between Mariana (Cierra Ramirez) and Lexi (Bianca A. Santos) only gets higher as the elections for junior class president inch closer.

Will Brandon and Callie reveal their secret? And how will Stef handle her cancer diagnosis? Fans will have to wait to find out. "The Fosters" airs Mondays at 8 p.m. EST on Freeform.