Beyond -- my sympathy for the pain you and your husband are going through. While all states have a statute of limitations regarding sexual abuse charges [deleted], I agree with the other forum members that your State authorities might be willing to interview the children at a minimum.
While I am concerned about the cousin's children, I am also very concerned about your husband. Has he had any type of counseling at all? You mentioned he has had significant problems surrounding the molestation, which is of course quite normal. Unfortunately, those problems never really disappear unless they are dealt with. The symptoms might be pushed underground for many years, but they affect our lives and, often times, destroy them if healing does not occur. Having experienced sexual molestation personally, I understand how very important it is to receive counseling in order to heal. I would urge your husband to find a good therapist which whom he is able to work through the issues that still plague him.
Please keep us informed and know you are in our prayers.