There's 2 areas that you need to understand and act on here – Nagging and Acceptance.
He's already explained his actions and done something about it. You can either accept this as the truth, move on with the acceptance OR continue nagging (as he sees it and something inherent in women) and accept those consequences.
What really is the end goal here? Could I suggest it's cutting done on his stress, learn to trust each other and work on yourselves to be better than you were before? The acceptance of his actions will be challenging for you due to insecurities however that's something YOU need to work on and try not to allow that to impact on your relationship.
Unless you know anything more suspicious about this text thing, drop it, accept it and mention it only if he wants to talk further about it. Dwelling on such things is going to eat you up. You've got better things to work on and head towards, don't you think?