That may be difficult and may not be easy to talk about, because women with gay porn is complicated, women can find gay porn or gay romances (yep, they exist, some of them quite hot, like the 'cut and run' series) attractive and hot, but not for the reasons you think. They may find two men having sex hot because they see themselves as part of it, the fantasy of it (since gay sex in porn tends to be pretty out there, huge dicks, elements of Dominance/submission to it) and they project themselves in, rather then be into actually wanting to watch it.
Some women who watch that stuff could very well get upset if you told her about yourself, feel threatened, the first thing a lot of women do is freak out hubby must be gay and is going to leave them if they find out (hell, lot of wives with hubbies who cross dress think that first and foremost).
Maybe one way is to 'catch her' watching gay porn and letting her know you are okay with it, and maybe see if she will talk about it eventually (they usually are way embbarassed about looking at any kind of porn, let alone gay porn) and maybe ask her if you can watch it with her, which will show you are curious and supportive. If you do that, then you can ask a question like "would you ever find it hot the thoight of me having sex with another man" as a hypothetical, asked without either judging (like "you watch this stuff, you thinking about me having sex with another guy" and her thinking 'oh, shit, he is pissed) or encouraging. It may take some encouragement to get her to talk, maybe tell her it turns you on that she is getting turned on, and see where it goes from there.
Women are a lot more open then they used to be and when it comes to bisexuality they tend to be more open then men are as a rule....introduce the topic gently, and see what happens, she might be interested in a MMF where the two guys interact, ya never know