I am a cuckold and I love my role, but it took awhile to accept it. Just be prepared, especially the first time she takes another cock, for the emotional rollercoaster you will experience. Yes there will be excitement on your part, sexual excitement, as you and your wife make plans for her to meet a guy for sex. That is part of the fantasy, since there has not been any real contact with another guy yet. On the day she will meet and be fucked by a guy, yes you will be aroused, but you will also start questioning whether you really want this. It is only natural, after all we are men and we do have egos. I would assume since this is the first time for both of you, she will meet the guy without you. At that point, you will have so many thoughts in your mind, sexual excitement of course, but also anxiety, regret, fear, a desire to call it all off. Those emotions are all normal, after all another man is going to have your wife, fuck her and she will come home (maybe with his semen inside of her)
Even though some think a cuckold is weak, and maybe we are, you need to be strong for your wife afterwards. No matter how you feel about the deed, assure her you are happy for her. Let her know you are there for her and if she wants to tell you about the experience, you are more than willing to listen. If she does not, accept it and do not press her for details. Whether she wants to continue in this lifestyle, let her know you support her decision one way or the other.