Is it normal should i tell my aunt the truth

My aunt always wanted to know who her real family was. She is in her late sixties.We always assumed she was adopted. Because that was what my great aunt told us. After her mother died, I found her mom's old journals and found out her mom( my great aunt) got pregnant out of wedlock and the real father dumped her. So she married her gay best friend so they would both have a cover. Apparently , he like to cross-dress which she wrote about alot.I also found some of his lady clothes hidden in the attic when I was cleaning out their house. She has no idea her parents kept this all from her.I had no idea they lived like brother and sister.They are both dead and she adored them. I don't want to hurt her.