By Don Kaplan and Nancy Dillon

Hollywood hellion Charlie Sheen is HIV positive and has been for years – but the virus is nearly invisible in his blood.

"He's alright. He's undetectable," one well-placed source said Monday.

The source confirmed that Sheen has been taking powerful drugs and responded so well that follow-up testing has failed to show the virus in his bloodstream.

That does not mean Sheen is cured, only that his treatment is working.

Another source told that Sheen has been safeguarding his HIV status for two and a half years while starring in his sitcom “Anger Management” and dating a conga line of adult entertainers.

The second source said third wife Brooke Mueller found out about the diagnosis after their separation and after Sheen went on his "Tiger blood" meltdown – but while they were still occasionally sexually active.

"I know she was shocked," the second source said, contradicting yet another source who said Mueller knew during the marriage.

Either way, the source said the couple’s twin boys were virus free.

The couple used in vitro fertilization (IVF) to become pregnant just weeks after their May 2008 wedding. Sons Bob and Max, now 6 years old, were born in March 2009.

“They did all the testing,” the source said. “The boys are fine.”

Attempts to reach Mueller directly were not immediately successful Monday.

In a panicked text message she reportedly sent to Sheen's former personal assistant, Mueller feared the actor "potentially" exposed her to HIV.

It's not clear when the alleged message was sent, but it refers to the couple being on a drug binge together at Sheen's residence and would have been prior to the assistant's death in 2012.

"I had a drug induced psychotic break at charlies after doing drugs with Charlie for that many days," said the text message.

I couldn't handle the HIV news. Just 6 months ago I was diagnosed with the eye disease and then Charlie potentially giving me HIV. I started doing heavy drugs with Charlie, staying up for days and it made my brain misfire," she reportedly wrote.

Mueller and Sheen divorced in 2011.

Sheen's prior wife Denise Richards also knew about his HIV status for "a number of years," said one source.

The actor reportedly the virus after he and Richards divorced in 2006. The couple has two daughters - Sam , 11, and Lola, 10. The girls and their mom do not have the virus.

Sheen reportedly doesn't know who gave him the virus. "Charlie thought he was indestructible and took no precautions- even though he was indulging in high-risk sex practices," an unidentified friend said.

Several women have claimed Sheen put them at risk, and the "Wall Street" star reached a financial settlement with one woman to buy her silence.

Ex-fiance Scottine Ross, an adult entertainer who goes by the stage name Brett Rossi, blasted Sheen for allegedly dangerous behavior in a video provided to The Enquirer.

"You exposed me to HIV for a year and a half!" she lashed out, according to the publication.

One of Sheen's former "goddesses" posted a Twitter message Monday saying she was getting tested.

"Recorded myself for half an hour being tested for HIV and getting the results. This is so stressful," adult star Bree Olson tweeted.

She was adamant last week that she was not infected.

"There are speculations circling that one of my ex boyfriends from years ago may have contracted the HIV virus. They are rumors and I know nothing more than anyone else," she wrote on Facebook.

"I, myself- have been to my gynecologist at least once a year since we split up and have always been tested across the board for everything and have came back clean," she wrote.

Sheen reportedly kept his status a secret because he didn't want it to overshadow his career.

"(He) has been tortured by the thought that his acting genius will be forgotten," a source said.

A porn industry source and former Sheen associate said Monday it was too soon to guess what Sheen might say to Lauer.

"Charlie is so unpredictable there is always the possibility he could go on 'Today' and deny the whole thing because this could hurt his ability to keep working," the source said.

"Given his past behavior, this might damage the ability of any production he is involved with to get insurance," the source said.

With Charlie Sheen reportedly about to announce that he has HIV, many people are asking about human immunodeficiency virus, the virus that causes AIDS. Here is some current information about the treatable, but still incurable, condition:

-- More than 1.2 million people in the U.S. are living with HIV — and 12.8% of them are unaware of their infection.

-- New cases of HIV has remained stable at about 50,000 new infections per year.

-- Roughly 1.2 million people in the United States have been diagnosed with AIDS. In 2012, 13,712 people with AIDS died.

-- Men sleeping with men are about 4% of the male population in the United States yet accounted for roughly 63% of all new HIV infections in 2010. In the same year, blacks (12% of the population) accounted for 44% of new infections.

-- HIV is treated using a combination of medicines in a treatment called antiretroviral therapy. Such medicines prevent HIV from multiplying and allows the immune system to recover.

-- The cost of treating HIV is estimated at $379,668 over the course of a lifetime. The government says that 30% of HIV patients are uninsured.