The father assured Grande that she is in no way to blame for the attack at Manchester Arena that left 22 people dead.
“You are no more responsible for the actions of an insane coward who committed an evil act in your proximity than you would be for a devastating natural disaster or acts of morons near your hotel,” he advised.
Millsap encouraged the singer to take strength from her family and friends before going public.
“When and only when you are ready, SING AGAIN. Music is the international language of peace,” he wrote. “Every time you open your mouth and share that incredible God-given gift to the world, you make this crappy world a little less crappy.”
Mr Millsaps is a film producer who lives in Georgia. His letter, which was shared on Twitter, has since received over 9,200 likes and 5,500 retweets.
This article previously appeared on marie claire.