A woman who says she was sexually abused hundreds of times by R. Kelly before she turned 18 testified Friday that she agonized several years ago about whether to cooperate with federal investigators who were looking into child abuse allegations involving the singer, but that she ultimately did because she didn’t want to “carry his lies.”But the witness — who is now 37 years old and going by the pseudonym “Jane” at the trial — also conceded that even after she began cooperating, she lied at one point when she told federal …