After a relatively peaceful breakup, things got kind of weird between Calvin Harris and Taylor Swift on Wednesday (July 13) after it was revealed that Swift co-wrote Harris' smash Rihanna collab "This Is What You Came For." Swift's camp confirmed that she helped Harris pen the song using a pseudonym, and shortly after, Harris also noted that his ex sang on it, too, while clarifying that he wrote the music, produced and arranged it.
Taylor Swift Co-Wrote Calvin Harris' 'This is What You Came For' Under Swedish Pseudonym
What was a polite reveal soon turned into a war of words that roped in Katy Perry and some clearly hurt feelings on Harris' part. His initial tweets were very complimentary.