Feelin some type of way but not knowing what type of way it is.

Lastnight I found out my cousin, the 2nd person close enough to be called friend , had sex with my lover. The lover that I've been secretly been messing around with for over a year. I mean I couldn't be mad at him, her, or hell not even my damn self . Not at him because I kind of knew what type of man I was dealin with before I got involved which would be a man thats been incarcerated since he was 18/19 & is now 28 so , in my eyes he's playin "catch -up" , he's promiscious(spell check) & selfish , not caring how he get it, where he gets it nor does he care anything about anyone else & there feelings so therefore by carryin on with him pretty much gave him & i approval that everything was cool & we could handle our "situation" . Now Her ,I mean me & him were/are a secret so she didn't know , simple as that. And Me , like I said I knew how he was before I met & took it to that level with him . I mean the whole situation was crazy because My cousin & I always joked around about how we were goin to "get" him , when in reality I got , was gettin him & just had him , but I never told her because I never been the type of female to air out all my personal business to anybody friend,cousin,mom , aunt , nobody .But I always felt if they were willing to tell me theirs i'd listen , take notes & keep my business on the hush. Anyhow we were always a secret because he was older than me & i was illegal at the time so thats where pretty much everything lies . But still I remain in some sence of shock , I guess it's because he knows we are close cousins & he still had sex with her regardless . But now im on the edge of how i should handle the whole situation. I think the best decision for me as of right now would be to cut him completely off without lettin him know why& jus keep it moving & jus one day down the line yrs. from now jus let them both know how i felt.