Abuse of 7 year old boy by female that was 15

My son is now 40 years old and has had problems every since he was around 7 years old. When he was youug he did not want to go to school, and as he aged it was alcohol and drugs, and his problem with alcohol and drugs has gone on for years. He never did want to be in a relationship with a girl, Well he met this girl and is in a relationship now, She told me last night that he broke down and told her that he drank and did drugs to forget what my 15 year old niece did to him when he was 7 years old. She would make him do cunnilingus on her, and this went on for a long time. My niece and I have always been close and she even works for me, but right now I hate her guts, this is eating me up inside.Any input would be helpful, I don't have anyone to talk to about this, because before if I needed to talk about a problem I would go to my niece Tweet