As far as I can tell and from what I know, "polyfidelitous V" with you as the hinge works fine (but you'll probably have to explain what it all means anyway). I've heard "polyfidelity" defined two ways: one, that there's no sexual activity except within the committed circle, and two, that no new partners will be added. You'll have to explain which you mean (or in this case, that you mean both). Semantics are often discussed and debated within the poly community, but most non-poly people have never even heard of these words, so, it's hard to boil your situation down to a word or two that will explain it to your friends, family, or whoever you come out to.
Polyfaithful, polyexclusive, and polytrothic are all new words to me, so I wouldn't know what to tell you as far as how they're defined, how you should use them, and if you should use them. It sounds like you can make your own judgment call there as you have done your homework. But again, you'll probably have to explain it to your audience, so just invoking a few words probably won't suffice.
I personally would use "polyfidelitous V" because that terminology is widely-known in the poly community. Something like, "We are in a non-monogamous relationship, two men and myself. All three of us know this and are okay with it. My husband is one of the men. The men just have a platonic relationship with each other. It's a 'V' configuration. It's also called polyfidelity, because we don't plan to add any additional partners, and none of us has sex with anyone except within our V." You could also call it a "closed relationship" to refer to the polyfidelitous (a.k.a. poly-fi) aspect.
No matter how you present it though, I think you are going to get some question marks, people are going to need you to repeat and re-explain things. You're probably mostly coming out to an audience that is completely unfamiliar with consensual/responsible non-monogamy (of which polyamory is a subset). People are going to be saying, "What? Who? You're what? How is that possible?" and other questions. Polyamory is often very confusing to people, because it's such a new idea in this monogamous world.
You're also likely to get some negative reactions from some people. Sad but true. There's a lot of monogamous conditioning out there, and many people just won't accept that non-monogamy can possibly be responsible. You just need to brace yourself for that, and give other people a lot of time to process the information. Sorry to have to tell you that.
Coming out is a tough job; not everyone does it. I'm still mostly "in the closet." So I have to applaud your courage. I hope my post here is of some help for you in preparing for this.
Love means never having to say, "Put down that meat cleaver!"