Over the weekend, Perry sent a series of tweets (that have since been deleted) accusing Gaga of not deserving a co-writing credit on the song. She clarified the allegation on Monday (Jan. 18) writing, "My sincere apologies. I made a mistake to comment. I wasn't in the room when the #TIHTY was being written." Perry added, "More importantly, I wish the focus to remain on the great importance of the song and the message of the film." See the tweets below.

On Monday, Perry claimed that Gaga changed one line in the song and that doesn't constitute a co-writing credit. She added, "I credit Diane for writing the song, it is her experience, her pain, her words."

Diane Warren took to Twitter following Perry's claims and wrote, "The song is the result of a special collaboration between myself and Lady Gaga. As Lady Gaga and I have consistently said. 'Til it Happens To You' was inspired by the countless survivors of abuse who need our support and love so they know they're not alone." See Perry's apology - here.

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