Keep the area clean and dry; it should heal soon. If the skin is truly raw--if it has peeled like a bad sunburn--then he should see a health care provider.
Washing right after sex (with soap and water, not bleach!) might help prevent some STDs, such as syphilis or herpes--but it's by no means certain. If your husband continues his extracurricular activities, condoms are the best protection--both for him and his other partners, and for you if you continue to have sex with him.
This forum doesn't get into marital advice. But it sounds like you and your husband might benefit from counseling.
HHH, MD
Ruby Baby,
Everyone knows that Clorox WILL NOT kill STD's. What your cheating husband should be using on his private parts is GASOLINE! Got a match? :-) Solve two problems at once here.