You need to call the police right away. DO NOT discuss it with him. He will probably lie, ask you why you are snooping, tell you its no big deal, or try to blame it on someone else in the household. Either way you will be left doubting what you saw and talk yourself out of doing something about it. If you have children leave with them when your husband is at work. The truth is your husband needs help. If he will chat about having s**x with children there is a chance he will actually do it. Keep in mind what he is doing is a felony and by not telling the authorities you are aiding him. I know you love him, but you must do something.