Charlie Sheen is opening up since revealing he was HIV-positive last November "I regret not using a condom the one or two times when this whole thing happened," Sheen told host Matt Lauer on the "Today" show "I regret ruining 'Two and a Half Men. I regret not being more involved in my children's lives growing up, which I am now" Sheen is now in control of his health and is receiving treatment for the disease every day