Out as gay, secretly bisexual - hookups with women

I'll keep this brief. I used to identify as bisexual, up until I realized that the gay men in my vicinity were heavily-unaccepting of bisexuality. I was more interested in men at the time, so I identified as gay instead of bisexual. It's been that way for six years.

There's one person who finally knows me not as gay but as bi. She's also interested in hooking up, and I'm definitely inclined to have a FWB arrangement. I'm uncertain how to bring this up to friends, though; I suspect they'll be shocked.

So, advice on coming out of the bisexual closet if you've identified as a gay man? Thanks so much!