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.

I wrote the music, produced the song, arranged it and cut the vocals though. And initially she wanted it kept secret, hence the pseudonym

— Calvin Harris (@CalvinHarris) July 13, 2016

Harris said that Swift "sings on a little bit of it too," dubbing his ex an "amazing lyric writer." 

And she sings on a little bit of it too --
Amazing lyric writer and she smashed it as usual https://t.co/vW3yGOIJit

— Calvin Harris (@CalvinHarris) July 13, 2016

Moments later, though, Harris took the gloves off and lashed out at Swift and her team for what he said was the "hurtful" way the news was leaked, lashing out at Taylor (and her team) for trying to "bury" him like she did to "Katy," a seeming reference to the alleged feud between Swift and Katy Perry.

Hurtful to me at this point that her and her team would go so far out of their way to try and make ME look bad at this stage though --

— Calvin Harris (@CalvinHarris) July 13, 2016

Harris then roped Swift's alleged new beau, actor Tom Hiddleston, into the mix, added that, "I figure if you're happy in your new relationship you should focus on that instead of trying to tear your ex bf down." 

I figure if you're happy in your new relationship you should focus on that instead of trying to tear your ex bf down for something to do

— Calvin Harris (@CalvinHarris) July 13, 2016

I know you're off tour and you need someone new to try and bury like Katy ETC but I'm not that guy, sorry. I won't allow it

— Calvin Harris (@CalvinHarris) July 13, 2016

Clearly stung, Harris tried to end his mini-rant on an up note, writing, "please focus on the positive aspects of YOUR life because you've earned a great one." 

Please focus on the positive aspects of YOUR life because you've earned a great one

— Calvin Harris (@CalvinHarris) July 13, 2016

At press time it did not appear that Swift had responded and a spokesperson for the singer could not be reached for comment.