Getting a divorce from someone with a top security clearance?

My husband and I live in Fairfax, Virginia and he works for the state department. He has a high level security clearance. I know he is cheating on him although he denies it. He’s threatened that if I try to bring him on adultery charges, he’ll lose his clearance and his job, meaning I would get no alimony. Is there a way to seal court records so that outside people don’t see why we are getting a divorce? If not, can I pursue a divorce for some other reason but still get alimony based on his conduct? He also travels extensively for his job and has said if I try to pursue this, he’ll just get on a plan and disappear, leaving me with nothing. How can I stop that from happening, would the state department help me locate him?