Calvin Harris is done playing nice with ex-girlfriend Taylor Swift.
Overnight, Calvin took to Twitter to address claims Taylor wrote one of his most popular songs. As it turns out, she did.
Taylor's reps confirmed the 26-year-old pop star wrote part of the Calvin and Rihanna hit, 'This Is What You Came For', under a pseudonym.
However, Calvin isn't particularly happy with this information coming to light, claiming she's trying to make him "look bad".
While the Twitter rant starts out quite friendly and sweet...
... It quickly descends into something uglier.
Calvin even brings up the notorious 'Bad Blood' feud between Taylor and Katy Perry.
WHOA! He did NOT just go there! "Someone new to try and bury"? Did Taylor try and "bury" Katy Perry for stealing her back-up dancers? (We can only assume that's "bury" metaphorically, like "bury" her career, not "bury" her body. We hope.)
Interestingly, Katy responded by posting this rather telling image.
She also re-Tweeted one of her old Tweets, saying: "Time, the ultimate truth teller."
Time, the ultimate truth teller.— KATY PERRY (@katyperry) May 9, 2015
Looks like Katy has been waiting a long time for someone to let the cat out of the bag!
As for Calvin, he wishes everyone a beautiful day. Thanks, Cal!