Hello and welcome out of the lurker's closet.
Originally Posted by Playmaker2
I am trying to be good about it, but I find myself getting angry and almost resentful at times, [...] I always remind myself that I knew my role in all this when it first started, and that this was the risk of such a relationship, but it's still tough.
First of all: I am sorry that you are hurting but I think you aren't allowing yourself to actually hurt as much as you obviously should. You just lost a love, so be angry, be resentful and hurt as much as you need to. It doesn't matter if you are secondary or what ever position you see yourself in. That doesn't dimmish your feelings one bit or make them less important. You invested your heart in this relationship, you have the right to feel the pain now that it is torn apart.
That is the personal dimension I am missing in your post. You are allowed to grieve the loss of this relationship and you should do so to be able to deal with it. Just trying to instantly be good about it will not help you (at least in my book).
Originally Posted by Playmaker2
How do people that are the secondary deal with the breakup of a partner, especially if they were the only one you're seeing?
I am sorry that I can't provide the view from a secondary position, I/we don't use those rankings in the first place. I know that it is quite common to consider the feelings of the primary partner more, but there are others who could tell you about that part.
But what I find quite disturbing is the strong veto power her husband had over your and her relationship. This would hurt me the most. Having my feelings been disregarded, and as you described it, even degraded by choosing and obeying to go with the wish of an outsider to your relationship would be really hard for me. The relationship wouldn't be valued by them and especially her in my opinion.
Well, that much about my (purely predicted) feelings on the matter. I know that there are valid reasons to behave like that and that there are some points that make her decision understandable. But even with those reasons in mind, I think that they are treating your relationship with her too lightly. She entered into a relationship with you, even if they couldn't predict how the real deal (you and her meeting in person) would feel like (and believe me, I really do understand how difficult this special kind of relationship is out of personal experience), they should have considered that dimension as well. That's why I don't understand why there is no resistance from her side.
So, how to handle it … well, I would suggest you do just like you would have done with the loss of an 'normal' (meaning mono) relationship. Some need to be alone to process things and stomach them, some need distraction of any kind to get over the first days and weeks. If you have trouble talking to your friends and don't want to tell them all the details, you could go with something like “there was another man in the picture” and leave it at that. It doesn't change the outcome, you can tell them that you knew that there was another right from the start and that she was unsure how to decide or whatever. You don't have to tell the whole truth if you need someone to talk about your hurt feelings. The hurt stays the same, even if you alter the story.
I told some of my friends that I am poly after I carefully discussed a purely theoretical polyamorous setting with them first. If I wouldn't know anyone to talk to about the real deal, the above suggestion would be my way to go.
Again: I am sorry you are hurting, I hope things get better soon.