Family dark secrets.

Annette • Just got my bfp with our rainbow baby 🌈
My cousin and I are very close and we was chatting today about the family. My dad is and always has been a heavy drinker and so is my cousins nan (my dads sister) my dad drinks everyday and gets quite angry and confrontational when drinking so I just thought it didn't agree with him. 
My cousin has told me today that my dad as a child was sexually abused by his dad (my grandad) I'm in total shock. My cousin says it's why my dad drinks as its a way of blocking out his childhood. My problem is I don't know what to do, do I approach my dad and try to talk to him about it or just leave it? I feel sad for my dad. My dad is a very proud man though and I'm worried of his reaction may be.