“From the first time we met, I knew (she didn’t!) that she was the love of my life forever….” he wrote alongside a slideshow of throwback images, ending his message by adding, “when I wake up next to you in our 80’s… I’ll smile at the life we’ve built,” he said.
McGraw and Hill share three children, daughters Gracie, 22, Maggie, 21, and Audrey, 17.
RELATED VIDEO: Still Crazy In Love! Faith Hill and Tim McGraw On How Date Nights, Prayer And Alone Time Help Keep Their Marriage Strong
The couple first met while performing on their 1996 Spontaneous Combustion tour.
“We were young and silly and goo-goo-eyed in love,” McGraw previously told PEOPLE about falling for each other.
Then while they were inside a dressing room at the Taste of Country Festival in Grand Junction, Colorado, McGraw popped the question!
“We’d been on tour for a while together, and I joked around with her about getting married. And so I said… I looked at her, grabbed her by the hand, and dropped forward onstage. She had already done her show and I said, ‘I’m really serious. I want you to marry me,’ ” McGraw said.
Although Hill had already finished performing for the night, McGraw had to leave for his set before getting his answer — but when he came back, the good news was waiting for him.
“I had in my dressing room this foldout case that had a mirror in it that was my dressing armoire,” McGraw recalled. “I still have it to this day. When I came back offstage, [I saw] a Sharpie with lipstick kisses all over it, saying, ‘Yes! I’m gonna be your wife.’ It had, ‘I love you’ with big lipstick kisses. And this is the place right here.”