I have a crush on my best friend?

I met this guy last year and we instantly clicked, he became my best friend. I was in a relationship when we met so I obviously didn’t look at him any other way.
I slept with his brother a few weekends ago (with his consent!). I’m starting to realise I only slept with him because he looks a little like my best friend.
my best friend tried sleeping with me after I slept with his brother (the same night!). It’s like he was jealous.

I’m actually a lesbian, this is where it gets more confusing for me. I only usually have crushes on women.
I love my best friend and I don’t want to risk losing him as my best friend if I told him I have a massive crush on him.
Any recommendations on what I should do? :(
I have a crush on my best friend?
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