Rooney revealed it all on Twitter earlier today:
In short, to confirm her suspicions that Vardy was the one leaking her personal stories, Rooney came up with a plan that involved posting some lies to her Instagram Stories, but only sharing them with Vardy.
Vardy didn't know she was the only one seeing these.
With this cunning trick, Rooney went from WAG to the most famous detective on the internet, now known for her incredible investigative skills.
She has since been dubbed Wagatha Christie.
Vardy has responded to the accusations on her own Instagram account.
"As I have just said to you on the phone, I wish you had called me if you thought this," she tweeted.
"I never speak to anyone about you as various journalists who have asked me to over the years can vouch for.
"If you thought this was happening you could have told me & I could have changed my passwords to see if it stopped.
"Over the years various people have had access to my insta & just this week I found I was following people I didn't know and have never followed myself.
"I'm not being funny but I don't need the money, what would I gain from selling stories on you? I like you a lot Coleen & I'm so upset that you have chose to do this, especially when I'm heavily pregnant.
"I'm disgusted that I'm even having to deny this. You should have called me the first time this happened."