Feldman serves as executive producer of the movie, and only ET was with him on set, where he opened up about why it was important to tell his and Haim's story, nearly eight years after Haim died of pneumonia.
"The only way I was willing to [be a part of this project] was with the understanding that the perspective came from both sides," Feldman tells ET's Cameron Mathison. "I said, 'Look, he is not here to tell his own stories, so it's really not fair to kind of presume anything...the only way I can sign off on this is if you go back to interviews from things he said out of his own words, and you used those to be the story points.' So as long as a script follows the timeline based on his own words, then I am OK with it."
"There is not going to be some great fabrication," he insists. "It is not dramatization. It's not going to be overly exaggerated for the purposes of drama."
According to Feldman, A Tale of Two Coreys is about his and Haim's "legacy."
"This is about... what kind of lives we lived growing up, what our lives were like, how they changed, how they were affected by being in the industry and the result and the aftermath," he explains. "From my side, it is also showing that I was a normal kid. I lived a very normal life, other than the fact that everything around me was crazy."
"It was about me trying to keep my sanity through the midst of all this madness going on around me," he adds.
A Tale of Two Coreys premieres Jan. 6 on Lifetime.