You might want to back out of it if it's not too late. You know how you feel when you fantasize about it, and then you cum. That's how you are going to feel the only problem is she will have been fuck. Once fucked there is no turning back. I loved it when my wife was getting fucked, but she decided not to do it anymore. I would have some jealous moments, but fortunately for me they were short lived. The only problem I had with the entire thing is she would not let him fuck her in the ass. He had a regular size dick, but he would fuck her so long and hard that I think she was afraid. Don't let a fantasy ruin your relationship. By the way I will say this the first time she fucked this guy was the most stressful. I was not stressed that he was fucking her, but I was stressing waiting on the details.