Incest or no incest, cousins are still blood relatives and I find it disturbing that some people would even consider engaging in such a relationship! People are seemingly absorbed with semantics here! The fact is, there is a greater chance for people who engage in sexual relationship with blood relatives, to have children with mental disability because of such close affinity.
Anyway, your husband has proven to be an unfit partner. Dump him. You'll find yourself better off in the long run. No point prolonging your agony because of your kids.