In an exclusive interview with TODAY, actor Charlie Sheen revealed he is HIV positive. "I have to put a stop to this onslaught, this barrage of attacks, of sub-truths and very harmful and mercurial stories that are threatening the health of so many others that couldn't be farther from the truth." Sheen told Lauer he has known about his condition for four years but decided to keep it away from the press. "It's a hard 3 letters to absorb," Sheen said. "It's a turning point in one's life."

RELATED: Charlie Sheen to Reveal He's HIV Positive

Sheen also admitted that he was extorted by others to have them keep silent about his HIV status, paying more than one million dollars to people he thought were in his inner circle to stay hush. He also mentioned that a prostitute threatened to sell a photo she took of his medication to tabloids. When asked why he made risky decisions such as sleeping with a prostitute, Sheen said: "I was so depressed by the condition I was in, I was doing a lot of drugs. I was drinking way too much. I was making a lot of bad decisions."

Sheen maintained that it is "impossible" that he has transmitted the virus to anyone, and that he has told every single one of his sexual partners since his diagnosis about his condition. There are "no exceptions," he said. 

Sheen also told Lauer he was not entirely sure how he contracted the virus. "I have a responsibility now to better myself and help a lot of other people," he said. "And hopefully with what we're doing with TODAY, some people might say 'Thanks, Charlie. Thanks for kicking the door open for us.'"

Sheen famously starred in CBS' "Two and a Half Men" until getting fired four years ago for publicly slamming show creator Chuck Lorre. The "Two and a Half Men" controversy went on to pave the way for Sheen's "My Violent Torpedo of Truth/Defeat Is Not an Option" tour and "winning" schtik. Though his personal life and substance abuse struggles made a lot of news at the time, he appeared to be cleaning up his act by 2012, when he starred on the series "Anger Management." He also worked alongside Lindsay Lohan, another actor with a party reputation, in 2013 comedy "Scary Movie 5."

As ATTN: previously noted, several famous figures have lived openly with HIV and "introduced the realities of the disease to popular culture," including former NBA player Magic Johnson. In 1991, when he was just 32 years old, Johnson surprised many when he announced that he was HIV positive. He continues to live with the illness today, and he hit a big milestone when he reached the age of 56 this summer.

AIDS was the number one cause of death for men ages 25 to 44 when Johnson announced he was HIV positive, and nearly 258,000 people were diagnosed with AIDS in the U.S. by the end of 1991. There was little known about how the disease spread when Johnson made his announcement in the early 1990s.