Something I've realized recently...i'm trying to find a way to explain it...
Most of the people on here, xeromag, polymatch forums, and and some local groups i've talked to, basically seem to work in 2 ways.
The first way, seems to be people who get into this whole thing who are basically hippies. They both, or all, feel that they should be free to love. And basically, working a 9-5 or time consuming job, limits their relationships to a usual 3-6 people. These relationships are USUALLY in the 1-3 year stage, but i've seen some who have been together for like 25 years, or enough time that the time they've spent together doesn't matter, cause it feels like forever haha.
The 2nd way, and most common(and i'll explain why later), seems to a married, grounded, or committed couple. They have been together for a considerable time, and one partner "discovers" that they are poly, or has always known but given the years, and growing feelings of mortality, they feel they can know longer hide their true nature. The one partner tells the other, and then drama ensues. It's usually a big test on their relationship, some fail, some don't, but alot of work is (usually) put into it because the partnerships has had years if not decades of investment
...which is what it seems to come down to in the end.
This is the most common topology because, in this growing social evolution we're all going through(some may even call it a regression, but whatever), there are a lot of changes. But even if change is forced, some residual traditions still linger. Take Jesus and his conversion of Judaism for example. The majority of people aren't poly...some are. And more are becoming so...and so naturally, people seem to find a way to make their "normal" dynamic into something that's natural and evolving for them.
I'm assuming you are part of the 2nd, and most common, group. So here's the catch. All the people that I see that are in WORKING relationships in that second group, have already sort of...progressed past the point in their relationships where there are trust issues. People who can swing, see their wife get decimated by another guy, and not really care or be threatened, because they're basically one person. The main part of that "one person" idea is TRUST. And you can't do shit like this with out it...if you try, it's just that much harder. I mean, some people simultaneously get over the hump of their poly transition while getting over their insecurity issues at the same time...but judging from your post, those people had more emotional fortitude than you.
You guys need to work your relationship before you can start another...it's really that simple. There's no other way to have it...This may seem unfair to your guy(and i would certainly feel that way too), it's a sacrifice he must make for your relationship so that you both can be happy in the future. You need to work on you guys first, get OK, then you can think about accepting another relationship in your lives(yes, you are a part of his relationships, regardless of your dynamic, because you are his partner).
Anyway...that's my 2 cents. I hope it all works out for you!!! GL
peace and love