I've been writing an autobiography about sexual abuse that happened to me throughout my childhood. The abuser was the dad of a famous singer. Once I was old enough (18) to leave home and file charges (I carried the abuse in silence as a child), my singer relative had become very popular. I didn't want to ruin his fame. Fast FWD 35+ years...the abuser is dead, the singer is still around, and I have a need to write this book without biting my tongue anymore. My story will not be about this singer, but yet feel it's important to mention the reason for me keeping silent all these years. I do not want any legal troubles. Would there be any by mentioning who the abuser was and why I remained silent for this long? Their hit songs title is very ironic to what I lived with growing up. Can I mention the song title as well?
I don't see any reason why you couldn't. The singer wouldn't have legal standing to sue you for libel. You're not saying he abused you, you're saying his father did. You're also not saying the singer coerced you to protect his career, that was your own choice. His father's estate would possibly have legal standing, but unless you wanted to take legal action against it, there wouldn't be any reason to go after you. His estate could counter-sue in an effort to get you to drop the case or settle out of court.
I think you might need to be a little more careful about mentioning the song.
I would be careful not to imply that the song is evidence that the singer knew about the abuse and did nothing about it. That seems like it might be worthy of a libel case.
You might get better advice over at the law section of Stack Exchange. https://law.stackexchange.com/