"Congrats, Baby!!!" Carey wrote. "I'm so proud of the person you are. You have pulled off the impossible. Record-setting tour, chart-topping album, amazing mother, and loving wife. I'm so sorry I'm not there for the last show but I'm so fortunate to be shotgun with you through the whole experience. I love you so much, and can't wait to celebrate life with you after the tour."
As incredibly thoughtful as Carey's letter was, Pink's reaction was just as adorable (and hilarious). "Thank you babe," she captioned her Instagram post. "I told the audience about this last night and we all decided that Hell has officially frozen over."
She hilariously hashtagged the post, '#handwritten' and '#whoareyouandwhatdidyoudowithmyhusband'.