This is one reason why cheating is a bad idea. You carry the guilt and self esteem hit for years.
Stop asking him! Being constantly asked would certainly raise both red flags and my temper. I assume he'll be no different.
Stop worrying about whether he trusts you. He knows you have cheated once, being the beneficiary of it. Start worrying about making sure you are worthy of his trust. Buckle down, concentrate on your relationship and deal with your feelings of guilt yourself.