Taylor Swift is viewed as country’s little, innocent sweetheart, but guess who “Mayer” change that perception?

John Mayer tells Rolling Stone that Taylor Swift’s song “Dear John” humiliated him, and he thinks it was a lousy thing for her to do.

Taylor’s song is widely believed to be about him after he briefly dated her in 2009… and the lyrics say things like “don’t you think I was too young to be messed with… cried the whole way home… and played by your dark, twisted games…”

Considering Taylor is known to write songs about men she dates, and she was only 19 at the time… Then 31-year-old John Mayer didn’t look so good.

John says he was caught off guard by the song and it made him feel terrible when he was already down.

Oh, and because he famously referred to Jessica Simpson as “Sexual napalm,” most people thought he had it coming.

The singer recently apologized for talking about women in his past, but now he’s after Taylor… calling her songwriting cheap and her lyrical revenge “bull s***.”

Geez John, who’s singing the sad song now?