Thank you for all of the responses.
lisbeth - right now, I am not looking for a boyfriend. Between working full time, having two young children and all that goes with that - I do not feel like I have the time to pursue other relationships. If it happens, I would be open to it - but I am not actively looking. Most of the men I meet on a daily basis are married and therefore I would not flirt with them.
I would eventually like to find someone. I would like to feel what my husband is feeling. Because I haven't experienced it (other than with my kids) I don't really understand how a person can love two people equally. But I would like to understand. My husband and I are still interested in swinging - though we don't have a lot of time to play. Also, the girlfriend has somewhat of an issue with it. However, that might be a good place for me to start. We'll see what happens. But am I open to it - sure.
Vandalin - I have actually lost it on a few occaisions. The most recently was two weeks ago when he took off work on his birthday and instead of spending it with me and the kids, he was with her. I didn't know he was doing that (he said he told me - I think this was a case of miscommunication) When I found out - I seriously lost it. I was screaming, crying, and told him we were done, took of my wedding rings and was serious. I was out of control. I scared myself. He left her to come take care of me and because he was concerned about the kids (they were sent to Grandma's so they wouldn't see what was going on.) Him and I fought, talked and eventually worked things out. But of course, the girlfriend was pissed that I melted down, again, and that he left her to come to me, again. And rightly so - I feel really badly that that happened. It was not my intent - I was out of control. They fought for a few days, but have since worked it out. She lost all trust and faith in me that I am trying to accept this.
I am trying to do whatever I can so that DOES NOT happen again. It was hurtful and stressful for all of us. I don't want to be like that again. As I said yesterday, they are on an overnight date, and I have been remarkably calm and ok. I kept myself busy and didn't worry or think about what they were doing. He called to say goodnight - and I told him to have fun. I hate waking up in the morning with him not here - but I'm doing ok. When he comes home today - I will welcome him with hugs and kisses and make sure that he is happy to be home. We then have a nice weekend planned that we are both looking forward to. THIS attitude I am having right now, is MUCH better than how I was two weeks ago. The issue is how to keep it this way.
Sorry for the long post again and thanks again for the help and advice.