The win ended a run of dismal results for the crisis club, with De Gea admitting he's not enjoyed seeing fans protesting against the club.
He said: "It's important not to concede goals. Today we were confident and deserved the three points. We need to start keeping more clean sheets.
"My mistakes are normal; I don't know anyone who doesn't make them. I do everything I can to help and save what I can."
Asked about the attitude inside the Fiorentina dressing room, De Gea was defiant: "For me, if someone doesn't want to play, he leaves, and someone else comes in."
And on the protests, the former Manchester United keeper also said: "It's tough, I'm suffering because I love football and I love this jersey and this city. I feel like a Florentine, and that makes it even tougher.
"No one expected to be in this situation, and that's why we need points, points, points. It's a long road, but we have to do it."