Do I tell him I read his book?

My friend introduced me to one of her brother's friends 4 months ago and we have been dating 3 months. He's so fucking fun with such a great personality. I found him on TikTok and found out he has over 600k subscribers. I went through his tiktok and found out he published a book about his crappy childhood. He's mentioned his childhood before but we never really talked about it. I know he has no relationship with his mom. I saw many comments on tiktok talking about how insane his book is. I feel like maybe I should have said I was going to get his book but I just ordered it off Amazon and read it and oh my fucking God. I found out about his entire messed up childhood in this book. He literally has a chapter titled "If I had a nickel for Everytime I was kidnapped and forced to join a cult I would have 2 nickels. Which isn't a lot but it's weird it happened twice right?" He talks about his mom kidnapping him when he was 9 and taking him to join a cult. His step dad holding knife to his neck when he was 14 because his mom decided Satan possessed him. Being taking away by CPS and getting SA'd at 14 in less than 24 hours of being in CPS custody. Getting into prostitution at 16 and so much more shit. I read his entire book front to back and I feel almost wrong knowing all this. Granted he published it. I want to ask about everything. We just had a Valentine's Day date and the whole time I wanted to talk to him about it but I have no idea how to bring it up.