Ha, yeah, sounds like you're one of us. I know exactly that sudden moment where that SOMETHING lights up and that's it, can't put it out, you know it's there now. And then suddenly you're fantasising about him with girls you saw on the street, girls in shops, your friends, even random imaginary girls, and it's scary how good but also natural it feels, like why wouldn't
you want this... yep.
Pandora's box? Yeah, maybe, but it's possible to be careful and wise in opening it. I've been through this before, myself, and there's a fair bit of collected wisdom from other 'queans who've done likewise but exactly what will apply to you will depend on exactly how your personal version of the fetish develops and how things play out. A good way to start is to say that it's completely okay to only want this as fantasy or as a naughty secret that stays between the two of you: there's no cuckqueaning law that says you've gotta get your hubby balls-deep in a real readhead within X months of you first discovering the urge.
Since you've already fantasised about this, you have some idea of the sorts of things you like about it, which is good for the conversations that might ensue when and if you bring it up to your husband. When most people hear the word "cuckqueaning" they hear "cuck" and automatically think of stereotypical male cuckolding - which I also find disgusting, so don't think you're alone there - as well as things like humiliation, the other woman mocking the cuckquean, forced bisexuality, and all that stuff. Some cuckqueans like that end of things (we call them "humiliation-driven"), but there's also the type of cuckqueaning that's all about the sheer giddy joy of your man fucking other girls, without humiliation (which we call "compersive"). They're not mutually exclusive, either - many mix a few elements from one into their main style, or want different mixes depending on their mood. There's a lot of different things we each like and things we don't; every 'quean has her own unique shape. So think about your fantasies, and think about what parts of them really appeal as well as what sort of things don't appear in them. Experiment inside your own imagination, just like you've already been doing, and remember the results.
As for bringing it up, the way I did it was in stages. My man already knew that I was cool with him looking at other girls; sometimes I'd even quietly point them out to him so we could talk about it, just like you did. It wasn't creepy or anything. To me when another women is beautiful or cute or sexy it's always been just a fact, another interesting topic, rather than a threat. Everyone likes having something in common with their spouse, and I don't know of any hetero man who doesn't like the topic of pretty girls. So we already had that, it was like a happy and comfortable hobby or shared interest. Sometimes he'll still shake his head and comment that he can't believe I'm not actually bisexual.
The next thing was to show curiosity and appreciation for his sexual background. I'd asked him from time to time about them before, not too much at once - it wasn't an interrogation - and once he felt comfortable about it I was able to get him to divulge some of the things he did with them. When he did, I listened, asked questions about things I was curious about, and told him sincerely when something sounded hot and that I enjoyed that he had experience before he came and broke me in. The important thing here is the sincerity; it's true that many men aren't tuned-in to the same things women are but they have their own way of listening (though often that way can be "sometimes"), and they'll be able to pick up subconsciously if you're faking enthusiasm. That shouldn't be a problem for you, since it's one of the things you want. Show your enthusiasm with touch: As he opens up, encourage him by touching his leg, stroking his chest, kissing his neck... all these things are hard to mistake as anything other than 'yes, absolutely tell me more'. Men deep down want to please and impress their women, and once he has the idea that his sexual background is something you appreciate and enjoy, or even are proud of, he'll be proud of it too. Obviously you don't want him to become a blowhard or brag about it, but that's down to his personality and your timing.
From there, it's escalation and encouragement. He points out a girl to you? Smile, nod, touch him, bite your lip, whatever you do to show him you're into him doing something. Tell him that you're happy he's with you and that it's natural for a man to notice pretty girls, so you don't feel threatened or unhappy. The key thing IMO is to phrase things in terms of HIS hypothetical attraction to them, rather than giving him the idea that you're bisexual (though don't get me wrong, it's cool if you are) and are merely letting off steam of your own. If things go well he'll become comfortable expressing that he's sexually attracted to other women (because he is) and will accept your assurances that this doesn't make you feel threatened, like he's going to cheat on you, or like you feel entitled to cheat on him. The latter point is important since many guys have heard stories of girls who use FFM threesomes to then later insist on MMF threesomes or encourage their men to go with other girls as a prelude for asking for a fully open relationship.
After all that, finding the right moment and method to tell him that you're presently imagining him doing things to that girl you just both discussed and are surprised to find you quite like the fantasy is much easier.
I hope that helped. It was still a bit long even though I kept back a lot of stuff we don’t know is relevant yet. Feel free to ask more, and to look around. There’s lots of good stuff squirreled away on /cuckquean/.