How can anyone make sure this doesn't happen again? This is part of the reason this is so hard. Trust, honor, loyalty... all of that has come into question and they are the basis for a marriage we all want. We all knew the restoration process was the hardest part of all of this because that is where the true work takes place.
Take it slow. Breathe. Trust is built. He needs to build it and honor your concerns and worries which are VERY valid.