"Hey Dad, it's ME. Tomorrow is going to be a tough day again!" Patterson wrote, and went on to reveal she had recently graduated university and beaten cancer.
A short while later, she received a response from a man named Brad who had lost his own daughter in 2014.
"Hi sweetheart, I am not your father, but I have been getting all your messages for the past four years. I look forward to your morning messages and your nightly updates," he wrote.
"I'm sorry you lost someone so close to you, but I have listened to you over the years and I have watched you grow and go through more than anyone. I have wanted to text you back for years, but I didn't want to break your heart."
The bereaved father went on to praise Chastity for her achievements calling her his own 'angel' after he lost his own daughter in a devastating car crash.
"You are an extraordinary woman and I wish my daughter would have become the woman you are, thank you for your everyday updates, you remind me that there is a God and it wasn't his fault that my little girl is gone," he wrote.
"He gave me you, my little angel and I knew this day was coming. Everything will be okay, you to push yourself every day and shine the light God gave you. I'm sorry you have to go through this, but if it makes it any better, I am very proud of you."
Patterson shared the touching exchange on Facebook and the post has since racked up nearly 300,000 shares.
"I text my dad every day to let him know how my day goes, for the past Four years! Today was my sign that everything is okay and I can let him rest!" she wrote.
"I shared my messages for my friends and family to see that there is a God and it might take 4 years, but he shows up right on time!"
