A mother whose daughter prosecutors say R. Kelly sexually abused starting when she was 14 told jurors Monday at the singer’s federal trial that she lied to a state grand jury 20 years ago, in part because she and her husband felt threatened by Kelly and feared for their lives if they told the truth.The mom, who used the pseudonym, “Susan,” in court at the trial in Chicago, described how she, her husband and Kelly were crying when the parents confronted the Grammy-winner at a hotel in the early 2000s about …