Why make a big deal about it? Why the official announcement?
Do you have any siblings? Of the opposite sex? Do you have a sister who drools over Zac Ephron or the Johnson Brothers or whatever they're called or whoever? Can't you randomly, casually hint at stuff, like when a sibling or friend is drooling over someone while you're watching a film or television series or music videos, you say, well, yeah, I like Vanessa Hudgens, I think she's hot, but if I were gay or bi I'd probably like Zac as well, he's quite cute for a guy...
Have you never had one of those random conversations about people's attractiveness generally, I'm not gay but...
I'd say 99.9 per cent of heterosexuals has an "I'm not gay but..."
And then it can kind of develop, like well, there's nothing wrong with being gay, in fact, I do actually think he's hot as well and I sooooooooo would...
I'm straight. Pretty much. I'm not gay but... I would sooooooooooooo love to kiss Angelina Jolie. And I'm not gay, but I almost got snogged by a German girl at a party once, she was really coming on to me and flirting with me, but someone else walked in the room...
Most people of younger generations are pretty cool with people who are heteroflexible - close friends of the same age might go through a phase when they feel threatened by it as they might be a bit confused about their own sexuality, but once they've grown out of that phase, it all should be cool. Oh, and also people in some of the bigger cities that have very high percentage gay populations are more accepting generally.
The older generation (and I am part of that older generation, I'm old enough to be your mum) some of them can be a bit small-minded, it's not necessarily personally against you or other heteroflexibles, it can just be that their own life experiences have been quite limited, and what you're going through is outwith their realm of experiences and they don't know how to react or deal with it.
Even though I am of that older generation, I'm from Manchester, England, which has a very high LGBT population, and I've had loads of friends over the years among that community. And I work in the media, and creative industries tend to have a higher proportion too. And a couple of exes have been bi/heteroflexible. It's not an issue, no big deal. If my daughter had told me she was gay or bi or whatever, I wouldn't have had a problem. But she's straight and recently married. Either way, I'm happy that she's happy.