Dave Grohl is getting raked over the coals on social media after publicly admitting he impregnated a woman who was not his wife. RadarOnline.com can reveal the internet has erupted into a chorus of “there goes my hero”, using Foo Fighters lyrics to express their disappointment in the band’s lead singer. The 55-year-old rocker made the stunning confession on Instagram Tuesday, writing: “I’ve recently become the father of a new baby daughter, born outside of my marriage.” Grohl has been married to former model Jordyn Blum since 2003, and they have three children together: Violet, 18, Harper, 15,…