It’s “One Hell of an Amen” forBrantley Gilbert— he has a daughter on the way!

The country singer-songwriter and his wifeAmberreveal to PEOPLE exclusively that they are expecting their second child — a daughter due in September — sharing photos from their sex reveal featuring 16-month-old sonBarrett Hardy-Clay.

But a snafu clued the dad-to-be in a little early, when a lone pink ball escaped ahead of the big reveal!

Brantley Gilbert and family.

Brantley-Gilbert-baby-1

“I didn’t see it,” Amber tells PEOPLE with a laugh. “I was so busy watching Barrett, but I saw the look on Brantley’s face. And then when the box finally opened … it was amazing. Therewas all this pink girl confetti, balls and stuff everywhere.”

Brantley Gilbert, wife Amber and son Barrett.

Brantley-Gilbert-baby-7

Brantley Gilbert and wife Amber.

Brantley-Gilbert-baby-2

Brantley Gilbert and wife Amber’s sex-reveal party.

Brantley-Gilbert-baby-4

Brantley Gilbert’s sex reveal.Lyn Sengupta

Brantley-Gilbert-baby-6

The moment was an emotional one for 34-year-old Gilbert, who was visibly teary in photos following the shower of blush-colored decorations.

“I know I have so much to learn,” adds the"What Happens in a Small Town"crooner. “You even diaper them differently, so I’m gonna be learning a whole lot of stuff from these books Amber reads — and I can’t wait!”

“I am just mush with Barrett,” he admits. “But I’m getting to where I’m okay letting him tough it out. I think a girl is going to be a whole new level of everything, and I’m ready. I already know she’s gonna own me, and that’s okay.”

Brantley Gilbert’s wife Amber.

Brantley-Gilbert-baby-8

Brantley Gilbert and family.Lyn Sengupta

Brantley-Gilbert-baby-10

Fifty of the couple’s close family members and friends gathered for the celebration, enjoying refreshments from aVarsity food truckthat Amber describes as “a tradition,” having used the company for their wedding rehearsal dinner and their sex reveal when she was pregnant with Barrett.

Most of the guests were team “Girl,” as barely any of the “Boy” pins had been claimed — and Barrett “loved playing in all the pink,” his mom recalls of the moments following the reveal.

“Earlier in the day, when they came with all the bunches of blue and pink balloons, we offered him a blue one or a pink oneand he went for the pink— almost like he knew,” Amber shares. “I’m not sure he understands, but it’s like he knew she was a little girl.”

Brantley Gilbert and son Barrett.Lyn Sengupta

Brantley-Gilbert-baby-5

Brantley-Gilbert-baby-3

Brantley-Gilbert-baby-9

For the second-time parents-to-be, it was the surprise of a lifetime considering their hunches told them Barrettwould be getting a younger brother.

“All I could think was about was me and my little brother,” Gilbert says. “And I have cousins where it’s just two boys. So even though at one point I’d thought it might be a girl, I’d really come around to the idea that it would be a son, and they’d be best friends.”

“I did too. I figuredthey’d be so close in age, they’dbe best friends. Just inseparable. Though with Brantley, a little boy and a male dog, I was feeling pretty outnumbered,” Amber tells PEOPLE. “I had three brothers, and I never got to do anything. I know Barrett isn’t going to remember being an only child because they’re so close, but I already know he’s going to be an amazing older brother.”

Of fatherhood, Gilbert says, “There is nothing like it,” musing, “And as great as you think it’s going to be, it doesn’tcome close to how it really is. To think it’s happening again is wild.”

source: people.com