Noted filmmaker Karan Johar has apologised profusely having written a chapter in his fallout in a biography with Kajol when she supported her husband Ajay Devgan in the middle of contest of Johar’s ‘Ae Dil Hai Mushkil’ and Ajay’s ‘ Shivaay’. ‘I should not have written that chapter’ Johar said adding that ‘I am really sorry’.