David Nail and his wife Catherine welcomed twins -- their first children -- in mid-December, but the couple had a long road to get to that joyous moment. In a new interview, the country singer and his wife open up about their "tremendous" struggles with fertility.

Talking with Nashville's Tennessean, Nail and Catherine -- who have been married since 2009 -- share the trials of their years-long quest for children. The couple looked to Nashville-area fertility specialists and tried in vitro fertilization, enduring unsuccessful procedures and an especially scary moment when, just before their first embryo transfer was to take place, Catherine was hospitalized after her lungs filled with fluid due to the treatments. Nail, who has battled depression and anxiety, admits that their trouble conceiving was tough to take.

“I was embarrassed for the longest time. A lot of what we dealt with had to do with me. And as a man, you definitely don’t want to hear that," he notes. "It’s your job to provide and be a husband and a father, and she had dreams of being a mother.”

Just before the 2015 ACM Awards, doctors implanted two embryos. While in Texas for the festivities, Catherine began feeling cramps -- the eggs implanting, she thought.

“When you’re trying to get pregnant, you’re watching for every possible signal from your body to tell you it’s pregnant,” she recalls. The first time, Catherine remembers, “I looked at David, and I said, ‘I think we might be pregnant'" -- but she kept it to herself when she felt it again.

A few days before a doctor's appointment, during which the couple would learn if the implanted embryos had taken, Catherine took two home pregnancy tests -- "the longest two minutes of my life," she remembers -- and they were positive. She surprised Nail with the news when he arrived home from a string of shows with a pair of baby shoes and the positive test.

“He was like, ‘What’s the Nike bag? What did you get?’ ... He gets the box out, and he sees the pregnancy test, and his first instinct is like, ‘Huh? Are you sure? We aren’t supposed to go to the doctor until tomorrow,’" Catherine recounts. "He totally second-guessed it."

On Friday (July 15), Nail will release a brand-new album, Fighter. The record's title track is a tribute to his wife, and the song "Babies" is for his son and daughter; in fact, the singer asked his record label to add "Babies," "Ease Your Pain," "Lie With Me" and "Old Man's Symphony" to the project following the birth of his children.

“I was just at a different place in my life,” Nail explains. He continues, "Suddenly you listen to this collection, and what you thought was a certain type of record that said a certain thing suddenly did a 180."

And while it was tough for Nail and his wife to see the situation's positives during their pregnancy struggles, the artist now admits, "there was positive all over the place."

"I used to tell her the good Lord will bless us to be parents when we’re ready to be parents, and there was a good chunk of that time I wasn’t ready to be a parent," he says. "I think He wanted to make sure that we got on top of that.”

2015's Country Music Babies