Ed Sheeran is facing a crossroads in his career as he testifies in his defense against plagiarizing a classic song.

The British singer-songwriter is currently in the middle of a lawsuit in which he is accused of copying a chord progression from Marvin Gaye's hit song, "Let's Get It On," in his song, "Thinking Out Loud," which was released on Sheeran's album x in 2014.

According to the New York Post's reporting of the ongoing trial, when asked what he would do if the court ruled against him, Sheeran said, "If that happens, I’m done. I’m stopping… To have someone come in and say, ‘We don’t believe you, you must have stole it’… [I] find insulting…"

He went on, "I find it really insulting to work my whole life as a singer-songwriter and diminish it.”

The plaintiffs of the case against Sheeran are the heirs of Ed Townsend, the co-writer of Gaye's song. During the trial, they brought in musicologist Alexander Stewart to serve as an expert on whether or not "Thinking Out Loud" copied "Let's Get It On."

Sheeran said of Stewart during his testimony, “If I have to be honest, what he’s doing here is criminal...I don’t know how he could be an expert. Obviously, just my opinion here.”

The star was also questioned about his writing process and how he collaborates with others.

If the court rules against Sheeran, this case will have major ramifications for the entire music industry. As The Washington Post put it, "The lawsuit and its implications are the musical version of saying to a painter: You’ll have to pay to use red. Someone else used it first."

As the trial continues, it remains to be seen which way the final decision will go.