My husband cheated on me six years ago with my old childhood friend

My husband cheated on me six years ago with my old childhood friend. I had a hard time trusting him for first few years after the incident. Lately I have this feeling that he might do something unfaithful. I had to check his email account that he forgot to sign off. Few notifications from Facebook were sent to his email account. I read some and found that he typed such inappropriate comments - "why do yo u have to show off your cleavage on the Profile on Facebook? ". Or "I don't mean sex. I'm sorry. I know you don't like hearing men talking about sex". It may be meaningless but is he really cheating again? He still doesn't know that I saw some of his emails.