The Portugal international quit the Red Devils in 2009 to join Real in an £80m deal.
Speaking of his move, Ronaldo told former United team-mate Rio Ferdinand: “I just thought in my mind ‘I want to go there to show my level, to show that I’m a different player’ and this is what I did.
“I arrived, I had a fantastic first season and I improved every season.
“But I never forget the Red Devils.”
And according to Spanish transfer outlet Don Balon, Real feel betrayed by Ronaldo.
Real president Florentino Perez is said to be furious with his star man over his comments about United.
Speaking about his move to Real, Ronaldo added: “When I became a Manchester player, it was a moment of maximum pride for me. But I think it was more for my family.
“At the beginning, winning trophies was very exciting for me.
“I remember when I won my first Champions with Manchester, the emotions surpassed me.
“Same with the first Golden Ball. But my dreams were getting bigger.
“I guess that's how dreams work, right?
“I had always admired Madrid and wanted a new challenge.
“I wanted to win trophies with Madrid, break all the records and become a legend of the club.”
