Hi there,
Hubby and I are new to this board. I was browsing through the forums and when I came across your post I just had to post something.
I feel your pain for this situation. Hubby and I had a very similar situation. Hubby was communicting with a female (a married female) that lived out of state. They were both communicating behind my back. The reason for this is because earlier in the year I had made it plain and clear that I was uncomfortable with this woman and I wanted communications to end with her. He agreed with me but obviously he didn't because he went behind my back and for 6 months was chatting with this woman via email and over the phone and I only found out about it because he decided to come clean with me and that was only because he was acting weird and I started to question his mood swings.
Well any way to make a long story short I guess you could say, things are better between hubby and I now. When I threated to take the kids and leave because I couldn't handle the situation with this woman anymore he took a long hard look at life and realized that the grass wasn't greener on the other side and he was about to loose the most important people in his life and this relationship with this woman was not worth loosing his wife and kids so the interaction with this woman ended. It also helped that just like your b/f this woman's true colors started to shine through and hubby saw her for what she really was and he started to realize that he didn't want to be around someone like that. Ever.
I'm glad things are better between your b/f and you. Swinging is suppose to be fun not stressful.