I have to agree. Communication is the key. Always was, always will be. You two have to sit and talk. Make a promise to each other not to get mad. No matter how mad you FEEL, don't get mad at each other. You have to be able to express your feelings to each other. If you don't tell HER that you are insecure, then she won't know.....and will continue to go forward. This will only serve to make you even MORE insecure, and eventually, you will split up. It is inevitable.
Through good communication, you will be able to squelch those feelings out.
My wife and I are at times brutaly honest with each other. I know that she likes to sleep with her boyfriend at the time. The reality about it is that I am HAPPY she is having a good time with him. Does this mean that she DOESN'T have a good time with me? Nope...Just that she is enjoying her time with him.
Now, Liz and I have certain boundries that we may not cross with our boyfriends or girlfriends. One of those things is kissing. We have historically reserved kissing on the lips for eachother. However, that was then...This is now. We are just now realizing that we are more poly, than we are "swingers". So now, we have developed a relationship with another couple. Well, with this advent, we are discussing the kissing thing. It is not easy to have the conversation. And sometimes, one or both of us shut down and want to leave the conversation. But we sit and stick it out. We still haven't hammered out all the details, but we make progress daily.
Now, not only do you need to communicate with HER, but also the boyfriend or girlfriend who is involved. This way, everyone is on the same page, and no-one's feelings are left out.
Remember, this is about LOVING EVERYONE in the group....Not one person giving up something, and not one person TAKING something. This is about communication and love. The more of each, the better.
Hoping you feel better soon....