I found out my husband has various of accounts open like,Facebook,MySpace,airg..etc how to get him to confess?

I lend my husband my phone ...When I got it back and was about to type a word it was a coincidence that an unknown user name type of name popped up..well after that I got curious to find out if he had any of these accounts open or anything ..I copied paste that user name on these websites and all of them lead to him. They have his pictures his information..on the Facebook one I decided to take a guess at his email &password and I WAS able to log in ..I started going thru it n it was so devastating to see this, all the postings, messages, ooohh..NOTE..;and his sister was one of his friends ...well I ASKED him about it n he denies it to the Max I can not get him to confess. He said its his sister that made this facke page ..I thought that could b probably b it but in my heart I believe its himthey both deny it .the sister saying it was her .but I think she's covering to him I know him very well all of his little phrases his ways of typing words,everything he's a single man on there he messages all these girls, he's in contact with one ex..I don't believe if the sister was making a fake page it would look so real like this one ...I just want him to be a man and tell. me the truth and its so hard living this way what can I do??