Mark, who is played by Channing Tatum in the movie, however, said he stands by his criticism of the movie that revolves around the murder of his wrestler brother Dave by his coach John duPont.
Schultz took to Facebook on Thursday, January 1 to say he was sorry for his words for director Bennett Miller.
"While I may have tweeted out of anger, I in no way regret standing up for myself, nor do I regret calling out the only other man who has had decision making power concerning my image and legacy these past years," Mark wrote.
Mark is unhappy with the film's suggestion that there could have been a sexual relationship between him and John duPont, who died in jail in 2010 while serving the sentence for Dave's murder.
"The personalities and relationships between the characters in the film are primarily fiction and somewhat insulting. Leaving the audience with a feeling that somehow there could have been a sexual relationship between duPont and I is a sickening and insulting lie," Mark had said.