well just get him alone and say ''im worried about loosing u too her'' and say to him how much u like him and wateva u do dont say tyo him ''DID U SLEEP WITH HER'' because other wise if he didnt then hell dump u for not trusting him so speak to wim and say that ur worried otherwise if he says no and u find out that he did then hes not a very nice person then lol. hope this helps
~*~scott~*~