How Can I Get Her To Confess?

About year ago, my wife, whilst drunk, confessed to sucking a young lads cock at house party.
I think she only told me as she found out that night that quite a few people knew her dirty little secret and she thought there was a good chance that I would find out.
The amazing thing was, it turned me on so much. My wife is stunning but, I always believed that she was faithful to me but, if she could suck a lad young enough to be her son, what else has she done?
I told her how turned on I was and begged her to confess more infact, just about everytime we fucked, I would say "Please tell me Baby, who's been fucking you? Who's cock have you sucked? Who's been eating your cunt?" She just gets angry and says no one. The other day when I tried to get her to talk, she went mad and told me if I ever bring up the subject again, she will leave me.
When I think about her with other men, it gets my cock so so hard. Any suggestions on how I can get her to confess, without bringing up the subject?