Most of that is either out of context or sourced from tabloids.

That first passage is her talking about her child marriage at 16 to avoid being sent to an orphanage, to a 22 year old guy she was not attracted to. Of course she wasn't impressed with sex.

This is the literal next sentence that is never included: “Now having fallen in love, I knew what I was. It wasn’t a lesbian. The world and its excitement over sex didn’t seem crazy. In fact, it didn’t seem crazy enough.”

In her diaries she also talks about being attracted to her husband, being in love with him, and mentions enjoying sex with a fling.

As far as being attracted to women, Natasha Lytess her acting coach with whom she supposedly had a relationship with: you'll never find her cited in any serious Monroe biography, as more than once she sold verifiably false information to tabloids about Marilyn after she died. She sold a lot of stories that talked herself up, and then started selling "Marilyn was in love with me". They did not live together for seven years like that site says, it was less than two. It was not odd for Marilyn to move in with her industry peers, for example she lived with her photographer and his wife for almost two years. Marilyn had a verified fling with a man during the time she lived with Natasha and started seeing her soon to be husband. On the other hand, multiple people have stated that Lytess was clingy and infatuated with Marilyn.

They were so close that Marilyn would hold her hand while shooting close-ups!”

If you spend enough time looking at photos of Marilyn, you'll find she loved to hold everyone's hand. She'd walk around holding photographers hands, her makeup artists hand, other actors on set.

I wish Marilyn was some lgbt icon, but as a big fan who has combed through almost every reliable piece of information about her I can find for years, she was not.