Dilemma

Hi all. I am 43 my wife is 36 and around 12 years ago I kind of tricked her into having sex with a coloured guy that I worked with at the time. He is older than us and has been fucking my wife 2 or three times a month, while I watch/join in, for the past 12 years. The problem now is that he says its going a bit stale and would like to see her being fucked by some of his friends of his as well. I have not told my wife about this yet(she does not know I am on this site) but I love the arrangement that we have at the moment (as she does) and have really mixed feelings about other men having sex with her as well. I have asked him for some time to think about this and bring up his proposal with my wife but my fear is if he stops coming around my wife and I may drift apart as it is keeping our sex life interesting. On the other hand if she starts having sex with other guys the same thing might happen. Any advice from anyone who might have had any thing similar happen to them would be appreciated.