Schultz hit headlines over the holidays when he took aim at Miller in a series of angry tweets about the movie.
The wrestling champion, who is portrayed by Channing Tatum in the film, revealed the director had refused to axe scenes that suggested he and manager John du Pont, played by Steve Carell, were intimate, stating, "I told Bennett Miller to cut that scene out and he said it was to give the audience the feeling that du Pont was encroaching on your privacy and personal space. It wasn't explicit so I didn't have a problem with it. Then after reading 3 or 4 reviews interpreting it sexually, and jeopardizing my legacy, they need to have a press conference to clear the air, or I will."
He ended his tirade by stating, "You Crossed The Line Miller. We're Done. You're (sic) Career Is Over. You Think I Can't Do It. Watch Me... You Think I'm Going To Sit Back And Watch You Destroy My Name And Reputation... You Aint' Seen Nothing Yet Dude... I Can Tolerate A Lot Of Things But I Don't Tolerate Disrespect. We're Done BENNETT."
Schultz, who was a consultant on the movie, was quick to apologise for his social media outburst, writing, "I apologize for the harshness of my language, but I am firm in where I stand. I will gladly go to any lengths to protect and safeguard the integrity and truth of my story, my life, my character and my legacy. If that's not worth fighting over while I'm still alive, I don't know what is."
The wrestler has now publicly apologised directly to Miller, insisting he was "temporarily insane" when he made the remarks about the Oscar-nominated drama, which also stars Mark Ruffalo.
Schultz tweets, "#Foxcatcher is a miracle. I'm sorry I said I hated it. I love it. I love my interpretation and will ignore the haters. I'm never getting mad...
"I think the problem I had was the context of the movie. It's what happened was so hard. My brother's murder. My career ruined. I feel terrible about what I did to Bennett. I should have followed God, not man.
"I apologize to you before the world Bennett. I'm sorry. I was temporarily insane."
The Hollywood Reporter: 'Foxcatcher' Subject Mark Schultz Apologizes for Criticism: "I Was ...