Herbert, who is now being sued by Contostavlos for allegedly being involved in the leak, has claimed that Edwards - aka MC Ultra - informed him of plans to release the footage at the end of 2011 as his career was "not getting any traction".
"I said to him that is absolute career suicide, you shouldn't be doing it, don't get involved in it," the ex-Spice Girls manager told BBC Newsbeat.
"Justin came back to me in February and said, 'No I'm ignoring your advice... and furthermore I've found some cowboys who are going to join an enterprise with me to put it out there'."
Herbert, who has since parted ways with Edwards, continued to stress that the sex tape release was "nothing to do" with him and said evidence from Contostavlos's team suggesting otherwise is "incorrect" and "can be challenged".
The former X Factor worker has been accused of trying to make up to £4 million with four other accomplices by selling the tape online.
Contostavlos settled her court case against Edwards in London earlier this month.