There is no such thing as making a deal with the devil. This is an expression that has been made over the years for people who get themselves into trouble. If you get yourself into trouble, it had nothing to do with making a deal with the devil. It was not using common sense!
I've been looking for the right answer for this question and it finally came to me.
You can't make a deal with the devil. It's not because he doesn't exist. It's because he'd be asking for your soul in exchange for whatever he gives you. You don't own your soul, God does. So whatever wager you've made is invalid.
So now all that's left to do is go to God and ask forgiveness for having bartered with his property. And don't ever do that again, okay? :)