The only way to resolve something like this is through communication. I recommend that you sit your Husband down to tell him of your concerns. If you do however feel that he might deny everything, there are ways to find out if he really is.
Go to this article to find out the many ways you could use to find out the truth. That is... if you really want to.
I also recommend Marriage Counseling after having talked with your husband of his affairs (if he really is). This however is recommended if you do want to work it out in the end, if not, then go for a divorce.