Disgraced rapper R Kelly was sentenced to 20 years in prison on charges of child pornography and enticement of minors for sex. Now the serial sex predator’s daughter has accused her dad of sexually assaulting her when she was just a child – and RadarOnline.com can reveal the horrific reason she has waited until he was locked up to come forward. In a new documentary, R. Kelly’s Karma: A Daughter’s Journey, Buku Abi, 26, claimed the abuse took place in Illinois in the early 2000s when she was 8 or 9 years old. She said: “He was my everything. For a long time, I didn’t even want to believe that i…