Sadly, the only way to know if jealousy is going to rear it's ugly head is to go ahead and swap then talk about it after. I know my wife was a little worried about jealousy at first as well. Well, not really worried, but when we talked about it she basically said, "I can't tell you how I am going to feel until I feel it. I can tell you all day long that I won't be jealous, but when I see you fucking another woman, I might be, I don't know. What I can tell you is, I agreed we are going to do this, so I will not hold it against you if I do feel jealous. We'll talk about it after it happens and go from there." Really, that's all there is to it. I'm not sure if truer words of wisdom were ever spoken. You can not predict how you are going to feel until you feel it.