Charlie Sheen admits he went on a ''suicide run'' after being diagnosed with HIV after seeking medical treatment for a severe headache, but now wants to help others. The 50-year-old actor, who isn't entirely sure how he contracted the virus, says it felt like ''a 'mule kick' to [his] soul'' when doctors first informed him he had the disease four years ago after he sought help for a ''debilitating three-day cluster-migraine-like headache'' amid fears he had a brain tumour. "I'm here to admit that I am in fact HIV Positive." -@CharlieSheenhttps://t.co/OVqVMKUGEThttps://t.co/10Ca6WRqt4— TODAY (@TODAYshow) November 17, 2015In a open letter published on the Today show website following his tell-all interview with host Matt Lauer, the former Anger Management star says he immediately went into a downward spiral even though he also began ''rigorous and intensive treatment.'' He wrote: ''The personal disbelief, karmic confusion, shame and anger lead to a temporary yet abysmal descent into profound substance abuse and fathomless drinking. It was a suicide run. Problem was, I'd forgotten that I'm too tough for such a cowardly departure.'' Sheen claims his ''viral loads became undetectable'' very quickly as a result of his medication and he is ''kicking this disease's a**.'' He wrote: ''Even though I might have been trying to kill myself, one thing was radically evident: the disease was not.'' The star paid blackmailers millions to keep his diagnosis a secret because he was ''locked in a vacuum of fear.'' But he added: ''I'm claiming back my freedom. The scales of justice will swiftly and righteously re-balance themselves.'' Sheen now wants to use his celebrity to help others and believes he can continue to lead a normal life. He wrote: ''In conclusion, I accept this condition not as a curse or scourge, but rather as an opportunity and a challenge. An opportunity to help others. A challenge to better myself. ''Every day, of every month, of every year, countless individuals go to work, man their stations, fulfill their professional obligations with a host of disabilities. Diseases, imperfections, hurdles, detours. These maladies range from lupus to cancer, from paralysis to blindness, from diabetes to obesity. 'Treated,' HIV is no different.''..