Ah - that explains the profile.
Yes I can understand why you'd be annoyed if you want to watch your wife with another man but it happened without you. Next time you and the wife are getting intimate why not mention how much it would turn you on to see her with another guy - and judge her reaction. If she seems interested you could say you think your mate really fancies her. If she knows that turns you on, if she has been naughty, she might confess but either way you'll be sowing the thought in your wife's mind and that might be the start of moving towards what you want.
I confessed to my wife years ago that the thought of watching her having sex with another guy really turned me on. For a long time it's been a bedroom fantasy. Recently my wife told me that she was ready for us to make the fantasy reality - which is why we are now on SH making contact with suitable guys. We haven't done the deed yet but we do think we've found the right guy to be my wife's first (though if she enjoys herself, hopefully not her last). So you never know - if you're honest with your wife but not pushy, where it might lead. You could set up a new joint profile on here and see if any guys take your wife's fancy.
Sorry - that doesn't answer the question about whether your wife has already had your mate but if she has (or even if she hasn't) and knows the idea turns you on, she might be prepared to let you watch her with him (or another guy). I hope you get what you want BUT before you ask the question be sure you want to know and can accept the answer. She's probably going to be embarrassed ( and might regret what she's done - if anything). If she has cheated, can you cope with that and move forward as a couple and maybe explore that further as something you want to share? Or will you resent her for cheating. What if she has strayed and regrets it and never wants to have sex with another man again no matter how much you want her to? How will you deal with that?
No easy answers I'm afraid but I do wish you lots of luck and hope all works out well for you both whatever has happened and whatever you decide to do going forward.