Looks like Charlie Sheen celebrated Father's Day by character assassinating former wife Denise Richards, who is the mother of their two kids, via twitter. The 49-year-old actor began his rant by tweeting that his third ex-wife Brooke Mueller was a sexy rock star whom he adores, but the 44-year-old actress is a "heretic washed up piglet shame pile," reported E! Online. The tweets got worse when the Anger Management star wrote an open letter to the media where he bashed the Wild Things actor by calling her the "worst mom alive" and an "evil terrorist." Despite of her former husband's awful behaviour, the Starship Troopers star killed him with kindness through her tweet, "Happy Dad's Day! @CharlieSheen have a great trip in Mexico! Kids were disappointed u weren't here for it. Hey we'll celebrate when u r back!"