I'm sorry that this is making you upset. If you know anything I can do to make this conversation less upsetting for you, please let me know and I'll do my best.
But since we know from you, over many times since you first started posting here, that you do not want to be sexual with men, how about we set male sexuality as a topic aside for right now? It seems to upset you, and it also just doesn't seem relevant to you separate from a longstanding pattern of self-harm with it.
In terms of homophobia, yes, I think that it is. Someone who didn't think they were gay, but also didn't have internalized homophobia, wouldn't be upset by the idea they might be gay, separate, perhaps obviously, from worries about discrimination it makes sense for everyone to have in a world that remains, by and large, deeply homophobic, heterocentric and heterosexist. Someone who thought they might be gay and who wasn't homophobic also wouldn't be fighting not to be.
Internalized homophobia or biphobia can often play out like this, where someone is okay with other people being something besides straight, but not themselves. Same goes for feeling upset about seeing other queer people being queer. Given your feelings, I'm not surprised it upsets you: you've been struggling with this for a long time, and I'm sure seeing people who not only feel okay about being gay or queer but also have the kind of relationship you want is very upsetting. It can be really hard to see people in the kind of space we want to be in when we've been trying so hard to get there without feeling like we can progress. <3
Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. - Margaret Mead