I think you have every reason feel hurt. Swinging is a big trust issue between two committed adults and when one breaks a rule, that trust has been violated. Even though your husband was in the heat of the moment, it was still something he shouldn't have done.
When Dave and I started out, we also had this rule. Oh hell, we had a lot of rules. I chose the rules and Dave said, "OK". He was totally willing to go along with whatever I said. If I'd said, no rules for anything, I would have gotten the same reply. I had all these rules, like no kissing (yes, I really did) and no anal and condoms always -- blah, blah, blah... I wanted these "intimate" things kept just for us!
Well, after talking to him, and after we'd played with a couple, all those rules went out the window (except the condom rule -- They will always be required!) We have our marriage that is intimate just between us. Our lovemaking is intimate just between us. We have SO many things that are intimate just between us that it almost seemed silly to put these restrictions on him. It was me that was having the problem with it, not him. Well, long story short -- I don't do anal with anyone except him for my own reasons. He can do anal with whomever consents to let him do anal. He's a great kisser. Other women should know how lucky they are to get to kiss him! Plus, it gives him pleasure and that's what it's all about for me. I love seeing him happy and to us -- really, it's just sex.
I'm not saying this is what you should do by any means. I just wanted to make sure you knew that there are many things between a couple that they do intimately with love that you may do with a partner that isn't love. Does that make sense?
There are so many things we share, like feelings and emotions, that I don't share with anyone else but him and vice-versa.
Other women and I may share his body and his talents, but only I have his soul.